You'll need to focus on infinity extremely frequently when shooting video. Establishing shots? There are probably adapters with optical elements that let you focus on infinity, but infinity focus is incredibly crucial.
I use a kit of nikkors on my 5D III: 28mm f2, 35mm f1.4, 50mm f1.4, 85mm f1.8, 135mm f2.8, which was as close as I could get to 18/25/35/50/85 Super35 equivalent in terms of FOV (that's the kit of focal lengths I'm used to). I also have a 24mm f2, which is garbage, and an 85mm f2, which is okay. The 105mm f2.5, which I don't own, is a gem. All have 52mm threads, which means ND filters are easy. The faster models have larger threads.
The sharpness is not great wide open on any of those lenses, but by f2.8 or f4 they meet or beat modern high end zooms with a little more flare, less contrast, and significantly better bokeh. They have a great feel. The only real issue is that most Nikon adapters allow focus past infinity, which will make any AC hate you because the focus marks will be wrong. So you have to write your own focus marks or shim your adapters. Nikkors are expensive at an average of $100-$200 per reasonably fast lens and dramatically more for exotic ones. Olympus/Contax is more expensive. FD or anything that needs an optical adapter is less.
Old lenses are a much more compelling buy for full frame than for APS-C because the 28mm is as wide on full frame as a 17mm is on APS-C. And you need something that wide to outfit a decent kit, but there are few old fast primes that are that wide excepting cinema lenses.
What I really, really want is a 21mm f2 Zuiko.