Open Bug 1435158 Opened 4 years ago Updated 4 years ago

Full screen Youtube video is collapsed when page is finished rendering


(Core :: Layout, defect, P3)

58 Branch





(Reporter: arv, Unassigned)


User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0
Build ID: 20160606113944

Steps to reproduce:

Open a youtube video page in a new tab (eg, The video element begins to play before the other page elements are rendered.  Click to make the video full screen before the other elements are rendered.

Actual results:

Once the page is fully rendered in the background behind the full screen video, the full screen is cancelled and the video is collapsed back to being displayed in a small element in the page as it was when the page was first loaded, before it was made full screen.  To return to full screen, I had to click again.

Expected results:

The video should have remained full screen.
Component: Untriaged → Video/Audio Controls
Product: Firefox → Toolkit
I'm unable to reproduce this , though the YouTube site could be doing something here that exits fullscreen.

Can you try to find if this is a recent regression in Firefox? You can run the mozregression tool ( to narrow down when this stopped working, though since it involves an external website there may be features of YouTube that aren't supported on older builds of Firefox which could make regression hunting harder.
Flags: needinfo?(arv)
It's been happening for many months (over a year maybe?), I believe since Youtube stopped playing flash video on my machine, so it's not likely a regression, and certainly not a recent one.  

I did check on Chrome on my machine, and it actually behaves the same way, so it might very well be what Youtube intends, or it could be a bug on both platforms, maybe related to something in Linux or Gnome specifically, or even to my particular installation (although I don't have anything out of the ordinary in terms of customization).  You said you could not replicate this -- is it because your machine is just too fast to click the video in the period before the page renders?  Or can you click to make the video full-screen before other elements render but it doesn't collapse back when the page is finished rendering?  If the latter, then clearly this is not intended behaviour from Youtube.  What platform are you using that doesn't exhibit this behaviour?  Thanks.
Flags: needinfo?(arv)
I was testing with Windows. This very well could be Linux specific. The bug very well could still be a regression that was introduced over a year ago as we have been working on fullscreen support.

Since this is happening on YouTube, which doesn't use our native video controls I'll move this bug to the Core :: Audio/Video component.
Component: Video/Audio Controls → Audio/Video
Product: Toolkit → Core
I had a chance to test with a fresh Windows 8.1 install, and the bug is present in both Firefox and Chrome on that platform as well.  I tried a few other video sites, but I couldn't find any that autoplay videos before the page is rendered...  So I can't say if it's a browser issue or just something Youtube does, maybe as a side-effect of their no-reload page navigation technique -- when they adopted that could very well be the time this started happening.  I'm fine with closing this as invalid if no one's interested in investigating further.  Thanks for your time!
Component: Audio/Video → Audio/Video: Playback
I can reproduce with today's Firefox Nightly on macOS as well. Dropping out of fullscreen (or doing something to trigger the site to request that) isn't a playback bug.

Bryce says he can reproduce on Windows Chrome, so maybe this is a youtube site bug. If we're different from Chrome here I think it's more likely a dom/layout issue. Redirecting for a second opinion.
Component: Audio/Video: Playback → Layout
[ Triage 2017/02/20: P3 ]
Priority: -- → P3
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