What are the options for manipulating video in live situation? Kinda like a VJ I would like to experiment with live videos when I'm playing as a DJ. I'm a windows user but I can migrate to GNU/Linux and I have money to spend on software. 

I remember trying Virtual DJ's video capabilities, but I wanted to know if there are alternatives. 

Also, I also remember watching a presentation on QUARTZ which is a Macintosh exclusive software for manipulating video live with complete midi control - he even explained how to hook a WiiMote to the software

So my question is: What are the options for manipulating video live?
The Max/MSP modular environment has a package called Jitter which is used for modifying videos in realtime. I've not had the chance to play with it myself, but I've seen it used in video art installations. Max supports several kinds of control such as MIDI and OSC, so I imagine all of these could be used to control video. 

You'll have to make your own patches though - it's not an 'out of the box' solution so much as a realtime programming environment.