I never had problems with BSplayer and avi files with corrupted structures..
Only very little problem I had with avi files with partial correct structure and last part missing. BSplayer was able to fully reindex the avi only by a small percentage, but the file was playable anyway
It's strange if the file is corrupted in the structure part but the error is on the movie size since the movie size is stored in the first part of the file while the structure/index is in the latter (if by structure you mean the P frames etc. index) :?