Videos can be a dynamic way to get concepts across to students for a couple of reasons. For one thing, students will be more engaged if they feel as though they are "watching TV" or doing something electronic, rather than listen to a spoken lecture. The need for technology in the classroom grows larger with each passing year.
However, the more important reason that videos are effective is that listening to the same speaker deliver lectures, day in and day out, can get quite monotonous. As a result, the students' level of absorption will decrease as time goes by. Using a video and a different speaker, with different sounds and cadences, will break up the drudgery and, perhaps, deliver the information in a way that reaches students differently than the every day teacher.
Here are two videos that would work in my class:
Good luck in the classroom!