I have found videos related to the material that are non-traditional get my students' attention. For example, this video is part of a series that can be found on YouTube about survival of the fittest and the importance of drinking milk. It was a fun way to start class and review the terminology in the evolution unit like "fitness" and "natural selection".
At a MNSTA conference I went to last month, I learned how to download websites. All you need to do is type the phrase "kick" in the address bar before "youtube.com" and it will bring you to another site to download it for free. It's nice to keep out the advertisements and for schools that have blocked YouTube on the Internet.