I was certainly concern that "someone else is teaching the class" when I use videos, and also that the person giving the Ted talk or whatever video clip I use would be much better than me and will make me look bad by comparison. But keeping the videos short keeps me in charge of the class and even a great speaker, on a short video, will be less interesting than a live person (me) in a small classroom. (This probably wouldn't work for a longer video which gave the students enough time to really start to like the instructor on the video, or a really big lecture hall where I was so detached from the students that I was almost like a video myself.) Remember also that you have to break up your lecture anyway since the students can't concentrate for 50 minutes at a stretch. Throwing in a couple of shot videos turns my 50 minute lecture into three 15 minute lectures with a 2 or 3 minute video between them. I have found that every student whose mind wandered came back for the videos giving me a fresh start for the next 15 minute section. I also found that something mildly funny, like a video of a person deliberately doing all the steps exactly wrong, cheers up the class while conveying the information in a memorable way that I probably could not use myself since I am normally demonstrating the right way to do it and could confuse someone if I was making deliberate mistakes.
