QPEG

Here is my QPEG decoder (module for ffmpeg). It is complicated RLE with 
very unusual coding of delta frames. There is one file from MPlayer 
repository which plays OK - qpeg-test.avi. Playing other tested files 
(Clock.avi, Space.avi, VWbig6.avi) leaves a lot of garbage on the screen 
- it seems to me that codec somehow cleans those areas (maybe using some 
previous frame). If you look in code you'll see a piece of code with 
comment "much of magic here, skipped for now", in disasm it copied some 
dwords from one location to another.

Can anybody figure this out ?
Thanks in advance.