Confirmed. I use a variant of Dsub on my Samsung SIII with Dolphan browser. I have two main Subsonic sites, one is Subsonic 4.7 beta 3 WAR version on Windows Server. The other is the Mashup Mod 4.7b3 3100 build. The sites are identical except for the WAR version used, one being stock for reference, the other being the modded version.
The unmodified site plays video normally, but the Mashup mod site displays the same video in half the screen and the control buttons are overlapped as you describe.
Fortunately, I don't use the phone very often to pull video on my phone as my Sprint bandwidth is usually too crappy to make even trying it worthwhile.