Part 1 of the great moNstrous-Video by Andrew dook Portner.
The reason why it's illegal to use Metamod in matches.
This is the original video with it's amazing soundtrack!

I am tired of answering all needless post like what's the name of this mod?
If you look really carefully at 0:15 - 0:21 the mod-name is on screen. Then just google monster plugin!