[jerf]

youtube-dl can download lists of videos.

It also automatically doesn't download things you already have, so it can be used periodically to sync the list if you want.

It only really matters if you expect videos to go down, but I also have my small collection of "videos that were obviously going to be taken down".

[dawnerd]

This is one of the best features (apart from channel backups).

I think because of its name people also don't realize that youtube-dl works for LOTS of other sites and it's relatively easy to add new sites in as well.