The video quality on the 6D is essentially the same that we've been used to and creating workflows around for the past few years. Yes, the sensor makes for some moire if you are shooting that type of patterned subject, and yes Canon really should have fixed that by now, but to say that if you'll be shooting video you need a Mark III is a little ridiculous.
This single failure ruins the 6D as a viable alternative to the 5D3 for professional video.
Seriously? I just shot for a week in Mexico with the 6D and the video turned out great. There was even a shooter with the Mark III who was blown away by the quality of the 6D's video in low light.
We get it, the 5D Mark III shoots great video, but saying that the 6D can't be used professionally because it has the same issues that other professional cameras have had for years is a bit off, in my opinion.