I have had great success extracting video from my TiVo. The DealDatabase forums have a lot of good information on the subject.

I am currently using TyTool Alpha5 (I think) at the moment. I have been using it for months and it works great. There may be a newer version, but since it works I haven't bothered to check.

There was a good guide on the net about using TyTool, but it seems to have been taken down. Luckily, I copied it to my webserver just in case that were to happen. I will send you a PM with the URL (don't want to make public for legal reasons).