JUST AS PRACTICE: I've uploaded my animoto here.
This past school year, we used You Tube videos for some of our teacher staff development. It allowed us to view and hear an explanation for activities we were responsible for completing. I can see this working very well for student use. Creating a web page or blog with a series of videos that walk a student through a step or stage of a lengthy, self paced activity would help keep kids on their own pace while still providing teacher instruction at just the right moment.
As for uploading student work, this was very helpful during a recent project our 8th graders participated in last spring. Those that created a movie on their apple were able to save and upload to You Tube for easier classroom presentation, where all we had available was a Dell. It also allows students to share their projects on a common playlist, allowing them to view and comment on each others finished work.
BTW: We start many many of our lessons with You Tube clips. While creating and uploading our own was the point of this lesson, the ones we use are more often those already posted by others. There is a series called 'They Might Be Giants' with several topics set to music. There is a lengthy collection of all the ending songs to any Bill Nye you would ever want. The kids LOVE these, and even up until the last day of school, they would ask "can we watch Timmy with the evil Global Warming?"