Recently both Apple and Firefox introduced Fullscreen support for the <video> tag in their development versions of the browsers, and these features can now be used with the new player for Wikimedia. The controls automatically show and hide, and you can even add and display subtitles with it.
How do I test it ?
It is rather easy, you go to this example video. If you want to enable it for all videos, you need to be registered on Wikimedia Commons or the English Wikipedia. You go to your preferences. Then select the "Gadgets" section. Now enable mwEmbed and Save.
The first image shows the player after the page has loaded. The second image shows the options for selecting and authoring subtitles. The third image is a movie with subtitles enabled. There are two modes for subtitles, either underneath the video, or drawn on top of the video.
P.S. The work is far from finished of course. I'm sure more refinement is coming, and the authoring of subtitles is only just getting started. Still I find that having it enabled on a daily basis is a positive experience, even with the occasional glitch.