Petapixel has an article and video that show the moire issues. Looks like the 6D is great for stills, but not so great for video, especially as an alternative to the 5D Mark III.
My 60D and the 7D already have the moire issue, so it still would be an improvement over them, but it sucks that they didn’t put the downsampling of the 5D Mark III, and instead went back to the cheaper and easier Line skipping which causes the issue to begin with.