Bien, Do you actually realize what your saying. I wonder. A video giving demonstration. That would be an educational video. So you would like me to go and organize such, hire a movie camera, blah blah blah.
Oh, please. Really?
No, he's suggesting that you ask one of your students to point an iPhone at you while you demonstrate. Or a Flip camera. Or any of a thousand other good quality consumer-oriented cameras in common use. It's just not that hard.