Though I'm mindful of the fact that you're in the UK and downloading video
may be something of a chore, I'd suggest you give The Open Video Project ( http://www.open-video.org/) a look.
There's a lot there but you could start by riffling through the Collections
(especially, the stuff from the Uni of Maryland ... I mean, really,
anything with Ben Shneiderman thumbprint on it would be a winner.
Bilingual Website Technical Writer
Ontario Teachers' Pension Plan
Email: Cheryl_Garabet at otpp.com