All five of these stills cameras provide some level of manual control, in itself signifying that these aren't low-level playthings. Often pro-spec, it's likely you'll need some existing camera, video and lens knowledge to make the most out of using these models for the best possible video capture.
Only the D7000 and GH2 provide continuous autofocus that's likely to appeal to the more casual point-and-shoot user, whereas the other models are big beasts designed for pro-aspiring users in the know.
Of the five models the Olympus E-5 is at the bottom of the pack (in fact lesser models will achieve far more). Its low resolution, low quality files and AVI format just won't cut it in today's market and this model feels out of date in a video capture world that's moving at a rapid pace.
A step above is the Nikon D7000. It's got plenty to sell it such as the continuous autofocus mode, but focus and fluidity of playback fall just below the mark at this price level.
The two Canon models are of a similar high-spec ilk, though the 5D mkII has unrivalled final quality thanks to its full-frame sensor. If quality is what you're after and full manual focus and controls are integral to you (an aspiring film maker, perhaps) then this is a great route to head down. Canon's lenses, while not to the same level (or cost) of, say, Panavision lenses, they are still staggeringly good and there are a whole host of wide aperture primes available that can take your shots to the next level.
For the more point-and-shoot minded the GH2 is the most successful marriage of quality and ease of use. The smaller sensor means files don't outdo the 5D mkII, but the Lumix's 24Mbps 1080p quality is up there with top of the range camcorders. Add to this the touchscreen control and silky smooth continuous autofocus and there's a whole lot to like about the Panasonic - it's the one most likely to banish camcorder rivals off the shelves.