I just posted a few videos that I made earlier this year using a Bamboo tablet and Mischief software with Screenflow. I like the software. Mischief is simple to use and it offers a infinite drawing surface with pretty neat zooming functionality. I like the effect, it can make a Prezi sort of fractal detail feeling, as though you are looking deeper into a sentence instead of on to the next page. In my most recent videos, I just wrote out the math and did a voice-over after speeding up the video. My intention is that a student could go through an explanation at talking speed and pause if necessary to take a closer look at the writing. Another eighty years and I'll have the whole course flipped.