Oh shoot, I'm sorry to have missed this question! Hopefully you're still around, although I imagine you may have found the answer elsewhere by now. The answer is that I recorded the one video over multiple sessions, as you stated, but I didn't actually talk while painting. I stitched the videos together in editing software, and then scrubbed/watched through the whole thing and wrote a script of things that would be relevant, and areas where I could go on somewhat less directly relevant anecdotal tangents. Once I kinda filled up everything I could say, I recorded it, dropped the audio in, then altered the timing of the various sections of the recording to fit. In other words, it was kinda movie magic, doing all of the important things at different stages. There were a few spots I think where I marked up what I had been working on - those I did afterwards, using keying (the act of removing a colour from a clip) to make it seem like I was just marking things up as I went. For this, I took a screenshot of the video recording, tinted the whole thing *very* strongly blue (so the keying would pick it all up, but so I could still see what I was marking up), and then drew on top of it in white. Once keyed, only the white remained. I hope that helps!