teachertube
There is definitely a space in the market for video content sites specifically dedicated to educators.
The concept is the same as Youtube but this site is only for sharing educational video clips.
There is a wide variety of materials currently on Teacher Tube, ranging from professional development materials for other teachers (e.g. discussing what are literature circles, using wikis, etc.) to more student geared materials.
Features that I like are the flag for reporting inappropriate materials and the ability to embed the video clips. I also like the guidance and position about posting copyright materials.
A problem with Teacher Tube is, like many other web 2.0 applications (like YouTube), it is important to question and evaluate the accuracy of what you are viewing. Just because a lesson is uploaded on Teacher Tube, it is not necessarily accurate or easier to understand. Additionally, if the service is free, the site is going to have to rely on advertising for revenue and it is fair to question if this will affect browsing through the website. Another problem that teachers may face is the download time to view and upload videos. The school will need to have good internet connection and have broadband to play the videos properly.
Teacher Tube has a potential to develop into a great online community for teachers as well as a much needed safe place on the internet for students to find "extra help" resources.