Used to work fine, so not sure if youtube did something naughty.

Now, I get
" Protocol 18&url=http is not supported."

For testing, the video in question is this

http://www.youtube.com/watch?v=BCHjbcgmugc&feature=relmfu

but it happens across a few videos.

Use recent version: http://aminet.net/package/comm/www/getvideo

aha. I'll test.