Online videos such as YouTube or Teacher Tube are great learnig opportunities. There is so much information to be found that can be beneficial to students. The key is too making sure that anything shown to students is previewed for accuracy, since just about anyone can post to these sites. I think the videos are beneficial because sometimes someone who has a different way of teaching or talking about a concept might be the one that connects with a particular student. Teachers all have different styles and not all students learn the same way their teacher teaches. For example, some math concepts that might be difficult can be taught different ways.
I know there is so much to learn on these video sites. The other day my daughter came and showed me how she had painted a "french manicure" on her nails. I asked her where she learned how to do that and she said, "YouTube!"
Converting and downloading vidoes is time consuming, so I am glad that our firewall now lets You Tube through.