Dialog box user/admin

Ok this is gonna be tricky and might be hard to explain, but let's give it a goal.
I'm gonna have a vide membership site, where i'm gonna teach music.
O single lesson page vere i plan to put videos, photos, some content, I also want to create a dialog box. So an user can ask questions while studying the lesson. This dialog box is suppose to be private and separate for each individual lesson. So every student can get individual answear to each lesson without having to search it inbetween other users questions. I think it may improve studying process. There may be an option to post some stuff to forum. But the concept is to keep clear history from each lesson which would help to measure the learning process.

Anybod know a plugin that could help to create such a dialog box, or maby some similar solution or even maby totally different solution which is 1000 time better. What anyboy think about that, maby it's worth trying to request such a function. Any feedback is priceless !!! :slight_smile: