I'm just wondering if going whole hog for a great lens is going to make a difference in video mode.

I ask this because, while I love the organic, filmic look of the 7D video I've shot so far, especially where the subject fills a lot of the frame (such as interviews), I'm not blown away with the resolution. I haven't tried to make things sharper in the camera or post, and focus is tough with the tools and the larger apertures, so this could be part of the 'softness' I'm seeing.

I can understand if you want sharp stills, but I'm wondering, in video mode where the resolution is so, so much less, if it really makes a difference.

I can also understand that image stabilization is important, and that constant aperture and 'faster' lenses are better. But given a f2.8, parfocal, and constant aperture and IS, is the $2000 lens going to look appreciably better in VIDEO MODE than a $700 lens?

IMHO, a higher quality lens buys you two things: a bigger aperture for low light shooting, and less falloff in the corners. If you buy FF lenses for a 7D, that pretty much takes care of the falloff. It's a bigger issue on the 5D2.

If you shoot at f/4, a $1k+ f/1.2 lens doesn't really buy you anything - especially on the 7D. On the other hand, if you shoot video in a cathedral on a moonless night, an f/1.2 lens would make all the difference.

Lens sharpness - especially in video mode (low res, aliasing) - is overrated.