One way that I like to use Youtube videos is to provide instruction from other teachers. That way students get another angle on the subject that might click with them a little better than the way that I teach. In fact, one teacher I know has made it her goal to provide instruction from at least three different teachers (including her own) through the use of videos so that students can get different perspectives and hopefully at least one of those will reach them.
One weakness that I often see in videos is that they often don't check for understanding. It would certainly be nice if we could just sit and absorb information (and we do to some extent), but it isn't the most effective way of learning. There has to be some sort of active element, even if it's only a short quiz or some guiding questions.
So, to practice this a little bit I created a lesson plan and assignment for French 2 students to review the passé composé with avoir and être (not including reflexive verbs). You can check these out for yourself at:
French 2 Passé Composé Review With Youtube Lesson Plan
French 2 Passé Composé Review With Youtube Worksheet