Russ, it's been explained by both Jeremy and me, that using a camera in video mode to capture the best moment of a rapidly changing scene is simply an alternative approach to setting the camera in 'continuous frame' mode. The advantage is, you won't fill up the buffer within a couple of seconds. The disadvantage is, there will be a sacrifice in resolution, and possibly dynamic range, but that shouldn't bother those who subscribe to the Ansel Adams maxim that there's nothing worse than a sharp image of a fuzzy concept.
Fine, Ray. Now show me an example of good -- I emphasize good -- street photography shot either in video mode or burst mode. I've played with burst mode in the past and I've never been entranced by the results. I'm talking about burst mode with the Nikon D3, which in 14 bit raw mode gives you a bit more than 9 frames a second for 16 frames. If you need more than 4 seconds and 16 frames for a street shot, you're screwed any way you slice it.
Luke understands the problem. Using burst mode or video mode is a mechanical approach detached from the situation. To do good street you need to be wholly captured by and involved in the action. Everybody seems to think that HCB was talking about an external event when he coined the phrase "the decisive moment." Actually, he was talking about the moment when the photographer is totally involved in the event and recognizes that it's reached the instant when he needs to capture it. The "decisive moment" is something in the mind of the photographer and in some ways it's almost like an orgasm.
For me, the 2mp frame size of an HD video 'still' is not enticing, because I'm a bit obsessed with resolution, which is why I don't use HD video for this purpose. However, my recommendation related to the new 4k video format with double the resolution and 4x the file size of standard HD.
If you understand street photography you'll understand that high resolution isn't a requirement. Look at HCB's early work. The film was slow, and even with dead-bang-on focus a lot of stuff is a bit out of focus because of shallow DOF. Compared with what's available now, resolution was lousy. And yet, people like Kertesz, HCB, Evans, Riboud created classics that stand alone. If you're shooting architecture or landscape you need to be concerned about resolution. If you're shooting street it's a minor consideration. I've attached a shot I made in 2000 with a Casio QV-3000EX, which had just come out. It has 3 mpx resolution. It makes a quite acceptable 8 x 10.
All modern DSLRs have a 'continuous frame' mode. Do you think this is just a gimmick, Russ, and an unsubstantiated theory of a method for capturing the 'moment'? 
I think video in a still camera is a marketing gimmick. We've had compact movie cameras for years. There was no reason to add video mode to a still camera, but the camera manufacturers were running out of gimmicks, like more and more pixels and jazzier focusing mechanics, and sales were falling. Being able to make a short movie with a still camera really appealed to point-and-shooters, and caused some of them to switch to more expensive mid-market cameras. It did give the industry a boost. Now that point-and-shoot cameras have been driven out by cell phones the industry needs another boost. What jazzy but unnecessary accoutrement will come along next?
