There's a webcam streaming WMV video that I can play/record with mplayer/mencoder (Debian Lenny including Debian-multimedia) just fine.

I'd like to capture the video such that, when played back, it's faster (so say 100s of real time zooms past in every 1s of video).

The "frameskip" filter seems like it ought to do this, but when I try e.g

mencoder -o output.avi -ofps 25 -vf framestep=100 -ovc lavc -lavcopts vcodec=mpeg4:... <mms source URL>

what I actually get is something which plays for the same length of time as it's allowed to capture for, but which only updates the displayed image every 4 seconds.

Is there any way mencoder can be persuaded to do what I want ?

(By the way, ideally I'd like to average the frames together to obtain motion-blur instead of just dropping/discarding most of them.).