I've actually tried that on Twitch, it was fun for another reason: viewer involvement. But as a format I found it didn't really work well because for my most impressive demos 90% of the time I'm just staring intensely at tiny fragments of code and trying to rearrange and run it in my brain - this is not interesting to watch believe me, I suppose one could condense the video to only show the ends of those segments and just talk out-loud about the concrete thought that has coalesced at the end of it and the actions that are now being taken.