I've never tried myself but I would start from mencoder (part of mplayer) and probably ffmpeg; there is an example for a simple Flash player on Freshmeat, see Video and Audio Streaming with Flash and Open Source Tools. The author uses MING which has Perl bindings.
I would not use Perl to grab video, I used ioctl to pilot the radio on my bt878 card and it was very painful :) Good luck!

update: see also Video::Capture::V4l.