IS is only to be able to shoot at a lower shutter speed in order to get a non-blurred image with stills photography. It has no application in video, because with a single CMOS, it's just going to jelly out before any IS/VR/OS whatever is able to smooth your image out. It's mostly only good on focal lengths longer than standard, so 70mm or greater. Any lower than that, and there's just not enough movement of the image while shooting handheld for it to entirely make sense.
on that note, riddle me this, Canon... why the FUCK are you coming out with IS versions of the 24, 28, and 35mm base primes rather than 85, 100, 135 etc that could actually use it?
hell... why not a 50mm f1.8IS? that would make far more sense than a 24 f2.8IS.. I mean wtf. At least on crop bodies it's a telephoto... a 35mm f2is barely even makes sense on a 7D.