A mash up video is when you put the audio from a song with another type of video. Here are some of the best ones I could find on the web.
5. Mario Brothers Meets Wu-Tang (Triumph)
4. Transformers Meets Dr. Dre And Snoop Dogg (Next Episode)
3. Hitler Meets Notorious B.I.G. (Freestyle)
2. Fat Albert Meets Notorious B.I.G. (Machine Gun Funk)
1. Ernie And Bert Meet M.O.P. (Ante Up)