It looks like Youtube is rolling out new functionality on the site allowing users to download videos.
The only example I can find currently is on Obama's Change.gov channel and Stanford's Lawrence Lessig blogs that this option will initially be available on "content that aspires to be consistent with principles of open government".
It's a bit of a vague definition so not sure of the full implications of this in the short-term or even whether it will be added to other content in the longer-tem. Either way I agree with Professor Lessig, it's definitely a great thing to happen.
Via Lawrence Lessig
Finally – although I really do hope it becomes more common than just Obama content.
I use video a lot in training, and YouTube is fine if you have WiFi and a high-speed connection. If not, it’s a problem and I’ve found getting content off the site at the moment is a hassle – really fiddly.