This is an incredible idea. I agree with @meno that
true and pure altruism is not long lasting.
So it's imperative that you focus on practical ways to reward the teachers. Otherwise, they won't stick around, and without them, you won't have students. A donations system will only go so far. I thin and SMT would be a workable solution to both rewarding teachers and keeping tutorials affordable for students.
I'd also say don't too much in a hurry. I understand the desire to be expedient and jump on the solution quickly, but going too fast can be detrimental. It's best to think it through thoroughly and implement it strongly.
What we want to achieve could be seen as a sort of donation system, but from peer to peer like Twitch. I hope that students/learners want to voluntarily pay for the tutorials that are actually useful to them, and not have to purchase tutorials first and then find out, it was a waste of money.
That's not a bad idea i guess from a student's perspective. I haven't used Twitch so I dont know how it works on a practical level.