YouTube has a great commenting system for users to communicate with  video authors, however it might be in your benefit to disable comments. While I'm a big supporter of free speech, I'm also an advocate of transforming questions into check outs. At the end of your videos, tell your users you will gladly  answer any concerns they may have, and tell them they can ask a question in the comment area  of the exact same page that your details link is teasing them to go to.