What video/audio software would Kutiman have used to remix youtube videos in thru-you?

I’m inspired to do something similar to kutiman in http://thru-you.com/ Kutiman remixes youtube videos of people playing musical instruments/singing etc to produce some pretty amazing music. I was wondering what the best audio/video software would be to try doing something similar.

I think Eztoo can help you.
Eztoo Video Converter supports almost all video formats as source files and outputs many different video and audio formats beyond HD (high definition), including MPEG, AVI, WMV, MKV, RM, MP4, ASF, iPhone, iPod, MP3, WMA, WAV, OGG, RA, AAC, AC3, etc.
You can download this software free from here:

http://www.eztoosoft.com/video-converter.html

For mac users:

http://www.eztoosoft.com/mac-eztoo-video-converter.html

Hope it helps. Contact me if you have any other question.

Debut Video Capture Software video tutorial