At last I have discovered a tool which allows my TiVo to download videos from a Linux system: pyTivo (the "wgw" version worked for me).

Unfortunately, I don't have anything that my family would like... Mushishi is about the only thing, but that is available on DVD.

UPDATE: While I'm enjoying the newly-found power a lot, not everything is smooth.

1. I am unable to make pyTivo to recognize compatible video and transfer it without transcoding.
2. Softsubs are a major pain. It's a good thing I always hunt for .avi, due to issues with VLC. But .mkv keeps advancing, and eventually it's going to be a problem, unless I learn how to make ffmpeg to render subtitles into the MPEG-2 stream.
3. The OGG is not recognized, and I have several videos in OGG: Kernel Summit presentations, lectures, etc.