I re-installed 1.72.0 for test purposes and tried out some more things. I found the following:
1. It seems to play MP4 and MKV files okay, but struggles with AVI files
2. Small AVI files play, but only sound comes out - no picture (although this may be encoding related, rather than size related)
3. Large AVI files don't play at all (although this may be encoding related, rather than size related)
I have included the files you requested in a Zip, uploaded to a filesharing site at: http://ul.to/zscyhv5b
Note that the file "Form 1.avi" only plays sound and the file "s8e01 - Jeremy Therapised.avi" doesn't play at all.
Note also that both these AVI files played fine immediately prior to these tests, using version 1.50.0.
Thanks for the help - I look forward to your diagnosis!