The issue may be with the conversion of the files and not the programs you're using. It's the most difficult part of the process. Unfortunately, many files that are grabbed of P2P networks are going to be tough to convert without a lot of programs and a lot of time. Doom9.org is one place to look for help on this.

Basically, your videos have to be converted to MPEG2 format. Usually TMPGEnc won't have much trouble, but if the file is compressed somehow, the program might not be able to read it.

I'd write more, but I'm late for a little trip. Hope you work it out and I'll be free next week too