Here are a small handful of synth-related videos. If you have more links, post them in the comments and I'll do a round-up in a few days.
Pink Floyd's Synthi AKS Dave Gilmour (now looking like a senior banker relaxing at his weekend house, but in the archive clips looking like the cool one from Radiohead) noodling on the sequencer of a Synthi AKS, demonstrating how 'On The Run' from Dark Side of the Moon came together.
Pete Townsend's ARP2500 Here's a young (and old) Pete Townsend from The Who playing an Arp 2500 and 2600 and a Hammond Organ and recreating 'Won't Get Fooled Again'.[WMV]
Vangelis' CS80: Here's a very short but wonderful clip [MPG] of Vangelis noodling on the CS80 and tinkling on what is probably his Yamaha GS1 (a primitive FM piano). It's pleasingly 'Blade Runner' all round.
Benny from ABBA's GX1 Mikey covered Roth Händle Studios a while back. It's a Swedish studio which looks after Benny Andersson's mind-bogglingly awesome Yamaha GX-1. Here [MPG] are a bunch of clips of them messing about with it.
Axiom's DSI Evolver 'Axiom' from the Electro Music forum bought a DSI Evolver. This [DivX] is him playing it for the first time, just flicking through the presets. For a very different take, here's Dave Smith himself playing.
Different Skies If you're after a some really grotty, mucky synth porn, then this [QT] is a 25 minute tour of the ultrageeks' gear at this year's Different Skies space music festival in Arizona.
(Thanks to Matrix Synth for many of these clips)