There is a documentary about Adrian Frutiger, I don't know if it's available in English though.. It's very interesting, you get to watch him flip through his old sketchbooks, help someone at Linotype tweak letterforms, etc..

Wow that's realy cool, I didn't know they made videos on typographers. I wonder if there's an English version.
Oh and I'm not sure if you're realy leaning on videos on Eric Gill but there are some of books on him and by him that are somewhat interesting.