UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36 OPR/42.0.2393.94

Example URL:
https://www.youtube.com/html5

Steps to reproduce the problem:
1. I reported this H264 Opera not working issue some time ago.
2. It was not playing h264 videos
3. I found a solution

What is the expected behavior?
https://bugs.chromium.org/p/chromium/issues/detail?id=677155&q=component%3AInternals>Media&colspec=ID%20Pri%20M%20Stars%20ReleaseBlock%20Component%20Status%20Owner%20Summary%20OS%20Modified

That was my previous report.

I've found the solution at this topics fifth post.

https://ubuntuforums.org/showthread.php?t=2347060

What went wrong?
Opera seems have some license issues but there is a workaround.

Due to licensing it's been dropped (they didn't or can't pay
To return - 
Get latest or current chromium-codecs-ffmpeg-extra package (install & grab from /var/apt/archives or go to ubuntu packages page
Extract it > inside extract the data.tar.xz file > navigate to usr/lib/chromium-browser.
Inside is libffmpeg.so copy it & replace /usr/lib/x86_64-linux-gnu/opera/libffmpeg.so with it (location is for 64 bit installs
screens show

Did this work before? N/A 

Is it a problem with Flash or HTML5? HTML5

Does this work in other browsers? Yes

Chrome version: 55.0.2883.87  Channel: stable
OS Version: Opera 42.0.2393.94
Flash Version: Shockwave Flash 24.0 r0

Contents of chrome://gpu: 
Graphics Feature Status
Canvas: Hardware accelerated
Flash: Hardware accelerated
Flash Stage3D: Hardware accelerated
Flash Stage3D Baseline profile: Hardware accelerated
Compositing: Hardware accelerated
Multiple Raster Threads: Enabled
Native GpuMemoryBuffers: Software only. Hardware acceleration disabled
Rasterization: Software only. Hardware acceleration disabled
Video Decode: Software only, hardware acceleration unavailable
Video Encode: Hardware accelerated
VPx Video Decode: Software only, hardware acceleration unavailable
WebGL: Hardware accelerated
Driver Bug Workarounds
clear_uniforms_before_first_program_use
count_all_in_varyings_packing
disable_framebuffer_cmaa
disable_post_sub_buffers_for_onscreen_surfaces
msaa_is_slow
scalarize_vec_and_mat_constructor_args
Problems Detected
Accelerated video decode is unavailable on Linux: 137247
Disabled Features: accelerated_video_decode
Clear uniforms before first program use on all platforms: 124764, 349137
Applied Workarounds: clear_uniforms_before_first_program_use
Mesa drivers in Linux handle varyings without static use incorrectly: 333885
Applied Workarounds: count_all_in_varyings_packing
Disable partial swaps on Mesa drivers (detected with GL_RENDERER): 339493
Applied Workarounds: disable_post_sub_buffers_for_onscreen_surfaces
Always rewrite vec/mat constructors to be consistent: 398694
Applied Workarounds: scalarize_vec_and_mat_constructor_args
On Intel GPUs MSAA performance is not acceptable for GPU rasterization: 527565
Applied Workarounds: msaa_is_slow
Timer queries crash on Intel GPUs on Linux: 540543, 576991
Limited enabling of Chromium GL_INTEL_framebuffer_CMAA: 535198
Applied Workarounds: disable_framebuffer_cmaa
Disable partial swaps on Mesa drivers (detected with GL_VERSION): 339493
Applied Workarounds: disable_post_sub_buffers_for_onscreen_surfaces
Accelerated rasterization has been disabled, either via blacklist, about:flags or the command line.
Disabled Features: rasterization
Native GpuMemoryBuffers have been disabled, either via about:flags or command line.
Disabled Features: native_gpu_memory_buffers
Version Information
Data exported	14.01.2017 16:52:32
Browser version	OPR/42.0.2393.94
Operating system	Linux 4.8.0-34-generic
Software rendering list version	11.17
Driver bug list version	9.15
ANGLE commit id	unknown hash
2D graphics backend	Skia/55
Command Line Args	--system-dpi-setting=96 --alt-high-dpi-setting=96 --enable-proprietary-media-types-playback --flag-switches-begin --flag-switches-end --use-turbo2
Driver Information
Initialization time	39
In-process GPU	false
Sandboxed	true
GPU0	VENDOR = 0x8086, DEVICE= 0x0046
Optimus	false
AMD switchable	false
Driver vendor	Mesa
Driver version	11.2.0
Driver date	
Pixel shader version	1.20
Vertex shader version	1.20
Max. MSAA samples	0
Machine model name	
Machine model version	
GL_VENDOR	Intel Open Source Technology Center
GL_RENDERER	Mesa DRI Intel(R) Ironlake Mobile
GL_VERSION	2.1 Mesa 11.2.0
GL_EXTENSIONS	GL_ARB_multisample GL_EXT_abgr GL_EXT_bgra GL_EXT_blend_color GL_EXT_blend_minmax GL_EXT_blend_subtract GL_EXT_copy_texture GL_EXT_polygon_offset GL_EXT_subtexture GL_EXT_texture_object GL_EXT_vertex_array GL_EXT_compiled_vertex_array GL_EXT_texture GL_EXT_texture3D GL_IBM_rasterpos_clip GL_ARB_point_parameters GL_EXT_draw_range_elements GL_EXT_packed_pixels GL_EXT_point_parameters GL_EXT_rescale_normal GL_EXT_separate_specular_color GL_EXT_texture_edge_clamp GL_SGIS_generate_mipmap GL_SGIS_texture_border_clamp GL_SGIS_texture_edge_clamp GL_SGIS_texture_lod GL_ARB_framebuffer_sRGB GL_ARB_multitexture GL_EXT_framebuffer_sRGB GL_IBM_multimode_draw_arrays GL_IBM_texture_mirrored_repeat GL_3DFX_texture_compression_FXT1 GL_ARB_texture_cube_map GL_ARB_texture_env_add GL_ARB_transpose_matrix GL_EXT_blend_func_separate GL_EXT_fog_coord GL_EXT_multi_draw_arrays GL_EXT_secondary_color GL_EXT_texture_env_add GL_EXT_texture_filter_anisotropic GL_EXT_texture_lod_bias GL_INGR_blend_func_separate GL_NV_blend_square GL_NV_light_max_exponent GL_NV_texgen_reflection GL_NV_texture_env_combine4 GL_S3_s3tc GL_SUN_multi_draw_arrays GL_ARB_texture_border_clamp GL_ARB_texture_compression GL_EXT_framebuffer_object GL_EXT_texture_compression_s3tc GL_EXT_texture_env_combine GL_EXT_texture_env_dot3 GL_MESA_window_pos GL_NV_packed_depth_stencil GL_NV_texture_rectangle GL_ARB_depth_texture GL_ARB_occlusion_query GL_ARB_shadow GL_ARB_texture_env_combine GL_ARB_texture_env_crossbar GL_ARB_texture_env_dot3 GL_ARB_texture_mirrored_repeat GL_ARB_window_pos GL_EXT_stencil_two_side GL_EXT_texture_cube_map GL_NV_depth_clamp GL_APPLE_packed_pixels GL_APPLE_vertex_array_object GL_ARB_draw_buffers GL_ARB_fragment_program GL_ARB_fragment_shader GL_ARB_shader_objects GL_ARB_vertex_program GL_ARB_vertex_shader GL_ATI_draw_buffers GL_ATI_texture_env_combine3 GL_ATI_texture_float GL_EXT_shadow_funcs GL_EXT_stencil_wrap GL_MESA_pack_invert GL_NV_primitive_restart GL_ARB_depth_clamp GL_ARB_fragment_program_shadow GL_ARB_half_float_pixel GL_ARB_occlusion_query2 GL_ARB_point_sprite GL_ARB_shading_language_100 GL_ARB_sync GL_ARB_texture_non_power_of_two GL_ARB_vertex_buffer_object GL_ATI_blend_equation_separate GL_EXT_blend_equation_separate GL_OES_read_format GL_ARB_color_buffer_float GL_ARB_pixel_buffer_object GL_ARB_texture_compression_rgtc GL_ARB_texture_float GL_ARB_texture_rectangle GL_EXT_packed_float GL_EXT_pixel_buffer_object GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_rgtc GL_EXT_texture_rectangle GL_EXT_texture_sRGB GL_EXT_texture_shared_exponent GL_ARB_framebuffer_object GL_EXT_framebuffer_blit GL_EXT_packed_depth_stencil GL_APPLE_object_purgeable GL_ARB_vertex_array_object GL_ATI_separate_stencil GL_EXT_draw_buffers2 GL_EXT_draw_instanced GL_EXT_gpu_program_parameters GL_EXT_texture_array GL_EXT_texture_integer GL_EXT_texture_sRGB_decode GL_OES_EGL_image GL_AMD_performance_monitor GL_ARB_copy_buffer GL_ARB_depth_buffer_float GL_ARB_draw_instanced GL_ARB_half_float_vertex GL_ARB_instanced_arrays GL_ARB_map_buffer_range GL_ARB_texture_rg GL_ARB_texture_swizzle GL_ARB_vertex_array_bgra GL_EXT_texture_swizzle GL_EXT_vertex_array_bgra GL_NV_conditional_render GL_AMD_seamless_cubemap_per_texture GL_ARB_ES2_compatibility GL_ARB_debug_output GL_ARB_draw_elements_base_vertex GL_ARB_explicit_attrib_location GL_ARB_fragment_coord_conventions GL_ARB_provoking_vertex GL_ARB_sampler_objects GL_ARB_seamless_cube_map GL_ARB_shader_texture_lod GL_ARB_texture_query_lod GL_ARB_texture_rgb10_a2ui GL_ARB_vertex_type_2_10_10_10_rev GL_EXT_provoking_vertex GL_EXT_texture_snorm GL_MESA_texture_signed_rgba GL_NV_texture_barrier GL_ARB_get_program_binary GL_ARB_robustness GL_ARB_separate_shader_objects GL_ARB_shader_bit_encoding GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ARB_compressed_texture_pixel_storage GL_ARB_internalformat_query GL_ARB_map_buffer_alignment GL_ARB_texture_storage GL_AMD_shader_trinary_minmax GL_ARB_arrays_of_arrays GL_ARB_clear_buffer_object GL_ARB_copy_image GL_ARB_explicit_uniform_location GL_ARB_invalidate_subdata GL_ARB_program_interface_query GL_ARB_vertex_attrib_binding GL_KHR_debug GL_ARB_buffer_storage GL_ARB_clear_texture GL_ARB_multi_bind GL_ARB_seamless_cubemap_per_texture GL_ARB_shader_draw_parameters GL_ARB_texture_mirror_clamp_to_edge GL_ARB_vertex_type_10f_11f_11f_rev GL_INTEL_performance_query GL_ARB_clip_control GL_ARB_get_texture_sub_image GL_ARB_pipeline_statistics_query GL_ARB_texture_barrier GL_EXT_polygon_offset_clamp GL_KHR_context_flush_control
Disabled Extensions	GL_ARB_timer_query GL_EXT_timer_query
Window system binding vendor	SGI
Window system binding version	1.4
Window system binding extensions	GLX_ARB_create_context GLX_ARB_create_context_profile GLX_ARB_fbconfig_float GLX_ARB_framebuffer_sRGB GLX_ARB_multisample GLX_EXT_create_context_es_profile GLX_EXT_create_context_es2_profile GLX_EXT_fbconfig_packed_float GLX_EXT_framebuffer_sRGB GLX_EXT_import_context GLX_EXT_texture_from_pixmap GLX_EXT_visual_info GLX_EXT_visual_rating GLX_MESA_copy_sub_buffer GLX_OML_swap_method GLX_SGI_swap_control GLX_SGIS_multisample GLX_SGIX_fbconfig GLX_SGIX_pbuffer GLX_SGIX_visual_select_group GLX_INTEL_swap_event
Window manager	Mutter (Muffin)
XDG_CURRENT_DESKTOP	X-Cinnamon
GDMSESSION	cinnamon
Compositing manager	Yes
Direct rendering	Yes
Reset notification strategy	0x8261
GPU process crash count	0
System visual ID	32
RGBA visual ID	93
Compositor Information
Tile Update Mode	One-copy
Partial Raster	Enabled
GpuMemoryBuffers Status
ATC	Software only
ATCIA	Software only
DXT1	Software only
DXT5	Software only
ETC1	Software only
R_8	Software only
RG_88	Software only
BGR_565	Software only
RGBA_4444	Software only
RGBX_8888	Software only
RGBA_8888	Software only
BGRX_8888	Software only
BGRA_8888	Software only
YVU_420	Software only
YUV_420_BIPLANAR	Software only
UYVY_422	Software only