Need to dub a youtube video.

Me and a friend of mine are starting a new youtube channel where we are going to make some comedy videos. We are starting off by dubbing over some videos with our own voices.

I just have a few questions that I hope you guys could help with.

I know how to download a video from youtube I know what sites to use, but I was wondering what software I would need and I would go about talking certain sounds off the video. What we want to do is just remove one voice from the video whilst keeping the backing music on and all the other voices, for example say in the video is tim and sue and some music, I want to know how to remove tims voice so I can insert my voice over it without affecting sue or the music.

Thank you for your help in advance, i hope someone can help

Connar

 

I know a website which might help. Search file to hd in google (sorry i cant posyt link ive just joined) and you can take videos straight from youtube to your hard drive. This also works for getting mp3's from myspace.
Hope this helps