Deal with HiDPI Video
I don't ctually have HiDPI screens to test, but I'm guessing either the layout is diffeerent, with the video smaller compared to the dialog, or it's lacking resolution and looks fuzzy compared to the rest (more likely).
While there's probably a multitude of approaches we can take, the simplest seems to render the video at half its nominal size so that there's enough resolution to play sharp at HiDPI when the canvas goes @2. This may become more of a deal when distros start shipping custom videos and we suddenly shrink it, so earlier we do this, the better :)