Examples: Liveleak.com, dailymotion.com
Youtube and Vimeo work fine, but on other sites when the flash video is toggled to fullscreen, it only goes fullscreen momentarily and then returns to normal. This bug only began after upgrading to Cinnamon 1.6.1.
In contrast, in Cinnamon 1.4, a new entry called "plugin-container" appears in the window list in the panel upon some Flash video going fullscreen, making the panel visible on top of the Flash video, but that didn't stop the video from staying fullscreen.
Flash version: 18.104.22.168-0precise1 (AMD64)
I see the "plugin-container" thing whenever I fullscreen any non-HTML5 video on Youtube.
I think it was fixed in 1.6.1 (issue #1159).
Unfortunately it wasn't. Now instead of the panel being visible on top of the fullscreen video, the video doesn't go fullscreen at all. It only goes fullscreen momentarily, then quickly closes.
I am running nightlies and have never seen a video fail to fullscreen, but I've never seen a video fullscreen without the panel, either.
There's still a problem: after going fullscreen, the flash content says: "press ESC to exit fullscreen mode", but the ESC button doesn't do anything, only after clicking one more time on the fullcreen video. Then ESC works again.
Issue confirmed to be caused by an extension (Maximus) and not CInnamon itself.