Okay, I'm going to call BS, for the most part.
First, I think it is legitimate to capture stills from a video stream. Of course, if you want to do it right, shoot in raw, and that means use a RED camera, not the "c". They mentioned this in the video and hoped for the next generation, when RED is already doing it.
Second, and they mentioned this as well, stills settings are nearly always very different than video settings for the same scene. One might want 1/500th for stills (for reducing motion blur in the final frame) and 1/48th for video (for preserving motion blur to make the video look smooth). This means it's nearly never possible to shoot video and stills at the same time with the intention of using both as final output. You are going to have to pick one or the other in advance most of the time. Again, though they mentioned this, they glossed over it.
Third, if you need flash for your images, video mode is not much help. Flash is often an incredibly valuable tool for controlling scene contrast, and we stills shooters often don't really realize just how powerful our little on-camera flashes are. If you want to replace a 580, you might need a 20kW video light, which comes on a truck. So this stuff is really only for conditions where natural light is acceptable without modification. Of course, there are many times like that, but not all by a long shot.
Fourth, capturing 24 frames per second and then picking your frame often does the exact opposite of what is mentioned in the video - it misses the key moment rather than allowing you to find it in the video stream. Not always, but sometimes. In many cases, I can time my shutter release to within about 2ms for doing things like capturing a batter hitting a ball, a pitcher releasing a ball, etc. For 2ms accuracy, you need 500fps, not 24fps. Even if I'm only accurate to 5ms (I can nail that most of the time) you'd still need 200fps. So, in many cases, "spray and pray", even at ordinary video speeds - or even at RED's maximum of 120fps - is not sufficient to capture the moment unless your "spray" is at very, very high frame rates that neither the "c" nor any of the RED cameras can manage.
I want to reiterate that there are times when this approach can be useful, but it's no panacea as they try desperately to imply in the video.