I think the fact that he posts the lessons for free after investing his time is cool, and the facial expressions are definitely a bonus. I say donate if you can... 50 people pony up $1 (just like buying a song from iTunes), hey--it adds up... now if Mark could get it to where we could download the vids for offline practice, that would be even cooler. Cooler still would be to see Mark as a featured artist on the Guitar World lick of the day iPhone app...
Mark--work that out, will ya?