I initially had the same terrible playback problems other people have had and I did the following, which solved my problems using both the Sprint stock rom and multiple versions of EnergyRom.
Here is what I did:
(1) I got CorePlayer, it was worth it for me because I watch a lot of movies when I ride the train and when I fly. (not sure if there is a free alternative)
(2) I installed the gfx booster mentioned in
Post #7.
-run the cab
-soft reset
-look for the program in your settings and open it and make sure it's enabled
(3) I installed some D3D drivers, you can also use the ones from
Post #7.
Or you can use newest
NeoS2007 driver pack. (here is the
xda thread where I got them) [I actually installed both, to see if it made a difference, I did not notice any, so I think installing the gfx booster and one of these D3D drivers is good enough, I have no idea if these make any difference for other programs, as I only was trying to get CorePlayer to play my xvid movies properly].
-run the appropriate cab
-soft reset
-DONE!
I have installed the 3 items in random orders with the same results. Just remember to soft reset after installing the drivers and gfx booster.
After that using CorePlayer I was able to play 700mb xvid files flawlessly, the audio was in sync there were no weird distortions or skipped frames.
I hope that helps some people
.