Hagen Graf, author of a German Drupal book, recently donated 700 EUR to the Drupal Association. This money comes from a German Drupal 5 training video that he made together with Video2brain. For every copy they sold, 1.25 EUR was set aside for the Drupal Association, and over the course of six months, this added up to a 700 EUR donation.
If you do the math, it is easy enough to figure out that they sold 600 copies in 6 months. So not only did they contribute 700 EUR to the Drupal Assocation, they also helped 600 Germans to get started with Drupal. A double hit!
Assuming that the above is correct and given that the DVD sells for 39,95 EUR a copy, it means that this German training video generated roughly 24,000 EUR in revenue. I don't know how much of that is left after they extract all the expenses, discounts and donations, but it does make me wonder about the potential of a Drupal training video recorded in English ...
— Dries Buytaert