Video clip for Steam's preview
) and also add things on that video, like third person, blur, or anything you have on mind.
Idk what you should use after that, maybe after effects? I never used any of those programs beside camtasia (only used camtasia to render really lol saves a lot of youtube upload time)
This program is mainly for editing your video, however, you should actually record it before, since what you get with the Source recording tools is only a .dem file, and thus only understandable by the Source games. I do this with Fraps. Another awesome program which is not expensive either, and really intuitive. You could record in Fraps what you are playing in the Source recording tool
Or to directly record scenes in game with Fraps.
It has a "multiplatform" version for Mac and Linux, idk how good it is though because I just use the windows version
Worth a shot, though !