http://bugs.winehq.org/show_bug.cgi?id=5137
--- Comment #14 from Angus Lees gus@inodes.org 2013-01-30 18:12:52 CST --- Yep, still exists in 1.5.22. The code has moved 15 lines lower in the file, but you can still see the same code/assert that I highlighted in comment 7: http://source.winehq.org/source/dlls/avifil32/avifile.c#L1475
The bug will continue to exist at least until that function is changed in some way.