I get the following error when I visit the page in site 2:

[10437:10487:0522/211740.896913:ERROR:render_media_log.cc(30)] MediaEvent: MEDIA_ERROR_LOG_ENTRY {"error":"FFmpegDemuxer: no supported streams"}
[10437:10487:0522/211740.897419:ERROR:render_media_log.cc(30)] MediaEvent: MEDIA_ERROR_LOG_ENTRY {"error":"FFmpegDemuxer: no supported streams"}
[10437:10437:0522/211740.897974:ERROR:render_media_log.cc(30)] MediaEvent: PIPELINE_ERROR DEMUXER_ERROR_NO_SUPPORTED_STREAMS
[10437:10437:0522/211740.899176:ERROR:render_media_log.cc(30)] MediaEvent: PIPELINE_ERROR DEMUXER_ERROR_NO_SUPPORTED_STREAMS

Am I holding it wrong?

Yes :) You did not enable proprietary codecs and that's an mp4 video.

You should add these two lines to your args.gn:
```
proprietary_codecs = true
ffmpeg_branding = "Chrome"
```

I have commented on the CL that I think is causing this: https://chromium-review.googlesource.com/c/chromium/src/+/1043546#message-988169fcf940c0069e698d76925f9c6470fcc01c

Thank you for taking a look! We'll have to rethink how to resize with aspect ratio as SetBounds() needs to be async.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/17982700ad2b8ed7b1c139ab80afdad17d15dd40

commit 17982700ad2b8ed7b1c139ab80afdad17d15dd40
Author: Jennifer Apacible <apacible@chromium.org>
Date: Fri Jun 01 23:10:16 2018

[Picture in Picture] Letterbox video during window resizing.

This change updates the way Picture-in-Picture window resizing is
handled.

Previously, there was an issue where OverlayWindowViews attempts to
resize itself in the middle of already changing its size, which puts
aura into a conflicted state.

This is an initial step towards allowing the window to adhere to the
video aspect ratio by just letterboxing the video. The window can be
of any dimension as long as it is constrained by the already given
min and max values of the window.

Bug:  845747   829677 
Change-Id: I6a120f3d346f7aa64909b06d5f48068497d8d7d7
Reviewed-on: https://chromium-review.googlesource.com/1080129
Commit-Queue: apacible <apacible@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563851}
[modify] https://crrev.com/17982700ad2b8ed7b1c139ab80afdad17d15dd40/chrome/browser/ui/views/overlay/overlay_window_views.cc
[modify] https://crrev.com/17982700ad2b8ed7b1c139ab80afdad17d15dd40/chrome/browser/ui/views/overlay/overlay_window_views.h
[modify] https://crrev.com/17982700ad2b8ed7b1c139ab80afdad17d15dd40/content/browser/picture_in_picture/overlay_surface_embedder.cc
[modify] https://crrev.com/17982700ad2b8ed7b1c139ab80afdad17d15dd40/content/browser/web_contents/web_contents_impl_unittest.cc
[modify] https://crrev.com/17982700ad2b8ed7b1c139ab80afdad17d15dd40/content/public/browser/overlay_window.h
[modify] https://crrev.com/17982700ad2b8ed7b1c139ab80afdad17d15dd40/content/shell/browser/layout_test/layout_test_content_browser_client.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/38a175872c91adb9eeedce02ca22d89563a4c9be

commit 38a175872c91adb9eeedce02ca22d89563a4c9be
Author: François Beaufort <beaufort.francois@gmail.com>
Date: Tue Jun 05 07:03:51 2018

Run Picture-in-Picture browser_tests on Windows.

Bug:  845747 
Change-Id: I46bae3d46de5478916719793b895d66aad40b36d
Reviewed-on: https://chromium-review.googlesource.com/1084212
Reviewed-by: apacible <apacible@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#564382}
[modify] https://crrev.com/38a175872c91adb9eeedce02ca22d89563a4c9be/chrome/browser/picture_in_picture/picture_in_picture_window_controller_browsertest.cc

mlamouri Can you make sure Picture-in-Picture browser_tests run on Linux as well?

fwiw I made a change that fails on one of these tests on windows bots only. because there's no linux coverage it's hard to me to test and iterate.

Sorry about that. It seems that the issue is specific to mash because we do not run VideoSurfaceLayer there on purpose. I will update the tests to only be skipped when Mash is enabled.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fe3bdcc0104f0530dcecc5c0f5054aac54a3dec4

commit fe3bdcc0104f0530dcecc5c0f5054aac54a3dec4
Author: François Beaufort <beaufort.francois@gmail.com>
Date: Wed Jun 20 00:21:26 2018

[Picture-in-Picture] enable browser tests on OS_LINUX.

This makes sures Picture-in-Picture browser_tests run on Linux but not
on Chrome OS yet.

Bug:  845747 
Change-Id: Ie22f3b5a3d3cebe9f2298b70882aae5e3679897b
Reviewed-on: https://chromium-review.googlesource.com/1105048
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568660}
[modify] https://crrev.com/fe3bdcc0104f0530dcecc5c0f5054aac54a3dec4/chrome/browser/picture_in_picture/picture_in_picture_window_controller_browsertest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d9fda94cd4a965385cc8089aaf798ffff7fa841e

commit d9fda94cd4a965385cc8089aaf798ffff7fa841e
Author: Mounir Lamouri <mlamouri@chromium.org>
Date: Wed Jun 20 13:22:49 2018

Picture-in-Picture: disable browser tests on mash.

This will allow the browser tests to run on all platforms.

Bug:  845747 
Change-Id: I07eb6fbd8240c5f559ef078538ffc047e7ab784c
Reviewed-on: https://chromium-review.googlesource.com/1105073
Reviewed-by: apacible <apacible@chromium.org>
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568815}
[modify] https://crrev.com/d9fda94cd4a965385cc8089aaf798ffff7fa841e/chrome/browser/picture_in_picture/picture_in_picture_window_controller_browsertest.cc
[modify] https://crrev.com/d9fda94cd4a965385cc8089aaf798ffff7fa841e/testing/buildbot/filters/mash.browser_tests.filter

The tests are now fully disabled on mash because video surface layer are not enabled there so the tests were always failing.