chirp, on Feb 7 2004, 12:03 AM, said:
5.Can I do it without eroding picture quality?
6. If it is possible, what program do I need?
If you have an alternate audiostream (with the language you want), you can exchange it with the old one using VirtualDub (for avi's) or TMPGEnc (for mpg's), since you just exchange the audiostreams, you don't need to reencode the movie.