Producing a decent 15 minute screencast takes hours of preparation. At decent billable rates, that means hundreds of dollars per episode. Plus these are videos with real value, that if they do their job, allowing the watcher to earn tens of thousands of dollars more per year.

As for free tutorials, you're a Google search away an essentially limitless library (many of which were written by some of the screencasters that make you sick). I've learned from free material, but I also feel that that an on-point screencast is worth a few dollars. That's why I'm more than happy to pay for RailsCast, Tapas, CodeSchool, and more, every month.

As for "should be free", I really don't know where you get this. In a world where information is a scarce resource, perhaps. That's not the world we live in, and I hope all that can add value all the best in selling their expertise.