As you surely know there is the cmd timescale ( default 1 )
which does the slow motion in single player when u start the a map in devmap. The problem is that when I adjust timescale from 1 to 0.25

/timescale 0.25

At the same time I record with fraps.
I try to open the video with K-lite and there is only a black screen with sound. the gameplay isnt shown. Should I make some changes in the MP options or use another capturing program? any ideas?

If you want to make a slowmotion video you're probably better off recording it in normal speed and then slowing it down in a movie editing program (Windows Movie Maker is free and comes with Windows, but there are other programs out there).

My guess about why this isn't working:
Fraps records a set number of frames per second. And maybe with the timescale set to 0.25 CoD just reduces the number of frames per second. Fraps then records "between" the CoD frames, leaving a black screen. Not sure, but that's just my guess

hmm so i 'll try setting fps in fraps to 25?

No, record it in normal time and then slow it down in a movie editing program.

I understood wat u mean but I dont wanna do it like this. In youtube i saw a vid called slow motion bullet time high ( if u might have seen it ) anywany he recorded with fraps and slowed it with timescale. I saw it on the vids comments . So wat other program can i use to capture while gaming?

You could try Camtasia.. but.. in the time it took you to wait all these posts, you could have done it easily already with the way I suggested.

well I just edited a clip captured with fraps in movie maker and i could play it inside move maker.Oh btw thanx for ur help once again Caretaker i appreciate it