Chrome Version: Version 62.0.3202.94 (Official Build) (64-bit)
OS: OSX

What steps will reproduce the problem?
Note: Exact steps to reproduce are not known.

- Create a (MSE?) HTML5 video with playable data
- Call play on the video node

What is the expected result?
Video should start playing and node.currentTime should start increasing.

What happens instead?
- Video does not start playing.

Note: 
- the node will emit both a play and a playing event
- the node will not emit any waiting events
- node.readyState is "HAVE_CURRENT_DATA" or higher.
- node.currentTime is within the node.buffered.start(0) node.buffered.end(0) range.
- webkitDroppedFrameCount/webkitDecodedFrameCount do not increase.
- node.paused is false
- node.ended is false
- node.currentTime does not change/increase
- node.error is empty and the node will not emit an error event

Any API callable from the JS application indicates that the video node should be playing, but it is not.

This may or may not only occur for MSE video playback (definitely experienced on MSE videos, not clear if also happens for progressive videos).
Exact steps to reproduce this are not known. In most cases the video will play as normal. At some point, triggered through an unknown condition, this will start happening. Once it happens for a single video, all videos on the same page but also on other tabs and even domains will show the exact same behavior. If you experienced this on Facebook, trying to play a video on YouTube will also fail and vice versa. Doing a full browser restart usually fixes the problem (we have some cases in which it reportedly didn't).

about:gpu and about:media-internals do not seem to reveal any additional helpful information and look "normal" (as for working videos). 

This behavior/bug was observed and triggered on both Facebook and YouTube. On Facebook this is the highest reported bug among employees. User bug reports for the same issue seem to be much lower. We suspect that it may be more likely to occur on OSX because of that, which is heavily over-represented among employees.