My workflow has been to link a youtube video, then immediately following, I create a "quiz" with only ~4 questions about the video to allow the students to demonstrate understanding of the concepts in the video. I use this as a formative assessment, to see areas where I need to focus, or give additional help to certain students.
Student engagement/buy-in is still challenging, even though there are assignments which are for report card marks and lecture videos only available online. I'm open to suggestions from others about this topic in the comments below...
For the students who have engaged - it is a good way to have a lighter view on the class topics - to find articles, youtube videos, or just comments and questions about science. It's familiar facebook-like appearance help in this case, also.
I will be doing more of a professional project around this topic, and creating a resource for the school admin and teaching staff which includes some research, interviews, and 'how-to' information. I'll be keeping the blog updated infrequently with details and findings as I work through the semester.