The test case exhibits two known-bad behaviors: (1) it opens more than 6 HTTP connections to the same origin (only 6 can work at a time), and (2) it does not properly clear the src of unused video elements (they may continue to hold a connection, see https://www.w3.org/TR/html5/embedded-content-0.html#best-practices-for-authors-using-media-elements for the standard solution).

I cannot reproduce this behavior on a recent build. It's likely that Chrome is doing a better job of detecting these idle players and killing connections, as we have been working on various mitigations for (2).

Chrome Canary does have MP4 support, so I suggest that you re-test there, however I suspect that clearing the src after thumbnailing will fix your problem.

So I pushed a new version. This one waits for `playing`, it then makes a thumbnail and calls `video.pause()`. There's an event on `pause` that calls

    video.removeAttribute("src");

The video element is then reused (or would be if there were move videos)

It still hangs for me in Canary

51.0.2692.0 (Official Build) canary (64-bit)

Removing the src attribute has no effect according to the spec; you must also call load().

Setting it to the empty string (video.src = '') without calling load also works, at least in Chrome.

Setting src = '' doesn't work. It generates an error trying to load the root of the website as a video

So removing the src attribute and calling load seems to fix the issue.

Thank you for that.

It's still a regression though. The original code had been running since last september and only stopped working 2-4 weeks ago.

Unable to reproduce, likely working as intended.