The fifth and final DPE session was today, so this collection is now complete.
See https://explainingmaths.wordpress.com/definitions-proofs-and-examples/ for links to all of the videos (streaming video, mp4 files, YouTube, iTunes …)
I was very careful to make sure my laptop was on mains power today, but the sound/video synchronization is still imperfect. I think it is pretty good until half way through, but drifts a little by the end. I don’t think this is a major issue, but I am puzzled by the cause. Perhaps I need a more powerful laptop to cope with the combined demands of Camtasia 7 and Bluebeam PDF Revu.