Know of any full length art videos?

That's a l-o-n-g time to be looking at something as fundamentally dull as making art! Those few artists who are happy to have people staring over their shoulders (eg. Bob Ross, Rolf Harris) tend also to be quick workers. Otherwise, time-lapse is pretty much the norm (for obvious reasons). Even on those occasions where TV arts programs concentrate on a single piece in creation they naturally enough mix in other stuff. This, for example, featuring Peter Howson, is just a part of a series in which Dawn French explored the whole subject of big women and is only 5 minutes and a bit long but says way more about the artistic process than anything of the length you stipulate. The truth is that the simple nitty gritty of applying paint to canvas or chipping stone, say, tells you next to nothing about art or artist, so you're extremely unlikely to find anything even approaching 2 hours!