Sorry, but anyone who is filming seriously will always have the time to focus properly and manually.
So professional wedding photographers, documentary photographers and sports photographers are not "filming seriously"? You seem to be assuming that photography is always (or maybe just mostly) at the center of the whole situation, something that is absolutely not true a good percentage of the time. Very often, we're just there trying to get the best images we can, in the middle of chaos.
Sorry, you misunderstood what I meant. When I said anyone 'filming seriously' I meant people that are shooting motion pictures. People here seem to assume that features that are made for still photography (auto-focus and exposure) should be included in cinema styled cameras, and end up assuming that the product is bogus because it's missing these 'standard' features, when the reality is, cameras in that price range are not for the market you're describing at all, these are cinema camera's with cinema lenses, for people shooting films, where every shot will be on a shot list, set up, exposed and focused manually (and pulled during the scene). Of course wedding photog/videographers, doco makers, and sports videographers are shooting seriously, but they won't be using a camera like the C300
Also as many people here have mentioned before, I don't really know anyone myself that actually buys a camera or lenses like this to use just for themselves. Most people will be renting them / renting them out. I work in advertising and gear is never bought to do a television commercial, always hired. We only have one video camera in house (an XF1) and that is just for stuff like vox pops.