The "internal player" in MythTV keeps crashing on me. Can't use it to "Watch Live TV" (which is an MPEG2 stream), can't use it to play back .iso DVD images, can't use it to play back .mpg files. Whenever I start one of these types, mythfrontend just disappears on me, and the mythfrontend.log file stops collecting data.
On the other hand, mPlayer does just fine with .mpg and .vob (DVD) files.
I have a sneaking suspicion that the player is trying to be too smart, and trying to use some utilities that the video card can't support. I've updated my MythTV playback profiles so it should use codecs, blitters and drivers that will work with my video card, but nothing has changed.