I don't see this in Chrome 57.0.2987.13. Lets see if a bisect reveals anything.

rehmandigri1952 @gmail.com

You can hit the star if you want to follow along.

@danakj -- Thank You for the report.

Tested the issue on Latest Stable# 56.0.2924.76 using Windows 10 and could not reproduce the issue. Toggling Play/Pause using Space is playing and pausing the video.
Could you please re-check on latest stable and provide us the update.
Thanks in Advance.

The problem is not that the video does not play/pause. It's that the play/pause button animation jumps between two positions while its animation advances. Did you look for that?

Hey Dana, I tried this on Windows 10 with Chromium 55.0.2883.0 and a fresh profile but I don't see any flickering.

Are you still able to reproduce? Can you try a fresh profile (or canary which installs side-by-side) and an incognito window?

(Not OP or on the Chrome team but was looking through the bug list) 

I suspect that either OP is on a slightly older computer, has bad graphics drivers, or has hardware accel switched off (maybe video decode accel is on, but 2D accel is off). I just tested this on my old ThinkPad T43 on a hunch and I can definitely say that the play/pause shape tweening isn't smooth. It's *trying* to be, but can't quite manage it given that the system is busy putting video frames underneath.

It might also be video-bitrate-dependent - the T43 can manage to animate more frames if there isn't much video motion underneath.

Specs: 1.86GGz Pentium M (32-bit), 1 core; 2GB (667MHz) DDR2; ATI X300 (RV370); hardware acceleration off (because it chews so much memory).

I suggest finding something with less-than-great graphics - ideally something like the above - to start with. A viable alternative might be QEMU with CPU throttling, but that would be a bit fiddlier to set up.

Right, I tried this again this weekend. It still happens for me on any youtube videos where the play button is the left-most button. If there is a button on the left of it (ie when you're in a playlist), then it doesn't repro. I tried reloading tabs and such and it continued to repro across multiple tabs/urls.

re #10, it's not that the animation is not smooth its that it jumps between two positions on (seemingly) alternating frames. It's not part of the actual video so it won't be video dependent. It's an SVG animation.

pdr@ would it help if I take a trace of this happening, or what would u like me to gather for you?

Dana's on a high-dpi device (2.5x) but I wasn't able to repro using --force-device-scale-factor=2.5 on ToT. Dana's going to try to repro in canary tonight, and double-check that this repros in an incognito window.

Dana got back to me and they weren't able to reproduce after upgrading chrome. We don't know whether this was a bug fix or some state that just got wedged.

I'm going to close this for now but we should reopen with vengeance if it comes back.