Have a read of http://www.gnutellaforums.com/348490-post9.html
So maybe the video itself looks ok, but ...

I read the post--good info. I've upgraded to 5.3 and still have good files killed.

I'm running on Linux. The check is killing anything that is mis-labeled--and a lot of content is mis-labeled.

There needs to be a way to disable this check because it's deleting files that are fine other than being mislabeled with an incorrect extension. Or is there a way to turn this off in 5.3?