amp-video with layout "fill" is broken

[jaspermdegroot]

What's the issue?

amp-video with layout="fill" is missing the source elements inside the generated video element after initialisation. Only after resizing the window they are added and the video can be played.

How do we reproduce the issue?

Test page: https://jsbin.com/soxunut/edit?html,output

Open the test page and you'll see the poster image in the output pane. Resize the pane or the whole browser window and the video will start playing.

The test page uses autoplay but the problem also occurs when adding controls and trying to manually start the video.

When testing with the output-only "live preview" (https://output.jsbin.com/soxunut) I don't see the problem, but the exact same markup tested locally without JS Bin does show the issue. It looks like JS Bin is doing something when initialising the preview that also triggers the source elements being added just like the resize event.

[Update:] Shift + reload often (not always) makes the video start after the reload, but it never works after a regular reload.

What browsers are affected?

Seems to be a problem in all browsers. Tested on:

MacOS / Chrome 59
MacOS / Firefox 54
Android / Chrome 59

Which AMP version is affected?

Tested with AMP version 1499361527811

[aghassemi]

Happens with other extended elements as well, not just amp-video. Assessment of root cause on related issue: #9397 (comment)

[ampprojectbot]

This issue hasn't been updated in awhile. @aghassemi Do you have any updates?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in 7 days if no further activity occurs. Thank you for your contributions.