iTunes Video Problem

I have a number of episodes of various TV shows that I've put on my computer using Handbrake (it's legit, I own the DVDs, it's just nice to have them on a computer). When I've burned them, iTunes has recognized them as movies, not TV shows, and I don't want to go through several dozen files individually. So on macrumors I found a program - I now forget what it is called - which does the trick by itself.

The only problem is after I tagged several of the episodes, they were no longer properly playable on iTunes, VLC, or quicktime. They're still on the hard drive, and take up the same amount of space, but now when I try to play them, there is neither video nor audio.

Has this sort of thing happened to anybody else? Is it remediable, or do I have to go through and reburn everything?

Thanks in advance. Sorry I can't remember the name of the Tagging software which caused the problem.