I don't entirely agree. The moire on the 5D Mark III is dramatically less than on all other Canon dSLRs, excepting the 1DC. It's no worse than most video-specific cameras; the other dSLRs are MUCH worse. It samples the entire chip (through binning) whereas others skip pixel lines. Because of that, the low light and moire reduction are worlds better than the other Canon dSLRs and on par with what you'd see in a 100% magnified still. Worlds better.
Resolution, DR, color depth, etc. is the same. But moire is dramatically better. Whether it's an issue for you is up to you, but I've seen that sample video's results repeated time and time again any time brick walls or fabric or certain textures of hair enters the frame. For more organic, low frequency material the difference is imperceptible. If you shoot certain kinds of material frequently, the 5D Mark III might be the only Canon dSLR that's useable. I've shot on the Mark II, 7D, t2i, t3i, a few Nikons, the GH2, etc. and pretty extensively. (Also, the Epic, F3, and I've done a lot of post with Alexa footage, which is the best of all by far.) And the GH2 and Mark III are the only two dSLR-type cameras without aggravating levels of moire.
The C100's HDMI is 8 bit. Only the F3, Alexa, and Red offer 10 bit log or 14 bit linear or whatever. Its c log is also fake log with the highlights compressed wrong and over saturated, whereas Sony and Arri have true log curves. That said, it looks like a nice camera and a more worthy, versatile upgrade for videographers than any dSLR, the 1DC included.
It took me a lot of use to notice the differences between the Mark III and the other dSLRs I shoot with, but the difference is there. How much have you shot side-by-side with both? I promise if you shoot both with the right material (such as the test posted above) you'll quickly notice a difference that is dramatic and significant to many videographers. What do you do when faced with fabric that induces moire? You can't always tell the talent to change or throw it out of focus -- and the problem is often less visible in the viewfinder than in the footage itself.
All Canon dSLRs (excepting the 1DC) still have poor resolution and DR and grade poorly in post relative to true video cameras, granted, and I agree the C100 is a more worthy upgrade for video. By far. But just because you don't need moire reduction and low light doesn't mean others won't.