Let school administrators and students know that the class is being filmed in advance. By giving notice, you prepare the school to have the necessary paperwork required by various government agencies that allows students to be filmed. Parents can sign a waiver stating that their child has parental permission to be filmed.
Bring in a camera operator. Having someone providing dynamic shots of your teaching and students' reactions is the best way to get an idea of how the classroom is functioning. If you can't find a camera operator, have several cameras set up where you can easily be seen and heard. Try a couple test runs by placing a camera on a tripod in various parts of the classroom and record yourself. If you only have access to one camera, place the camera in the class at an angle that will allow viewers to see the teacher and also get an idea of the classroom environment and the students in the class.
Teach the class as you normally would. It can feel awkward and strange for the first few minutes as the camera is turned on. The need to do well may inhibit you from actually teaching the class as you usually do. Focusing on teaching students instead of the camera or the possible evaluations. As you get comfortable with the camera it will no longer be a concern for you and it will be easier to teach your students the same way you had been teaching before.