Video with transparent background walls

[DeNeDe]

Hy there,
How can I make(encode) a video to have transparent background(walls)
I have a demo(record video) from counter-strike 1.6 and i want to make the walls transparent so i could see the players through the walls.. in the video, not in the actual game..

[Keiyakusha]

Recorded video is a set of images. If you recorded it while walls wasn't transparent - you can't do anything about it.
Make walls transparent in game then record video.

[DeNeDe]

that means using hacks :(