[EDIT 10/3/2012 – I removed the links to BubblePLY. After trying it out again, I got virus warnings. My old video links directly to the download page now. Overall, I just have bad vibes about it and I don’t want anyone going there off of my recommendation. However, Screenr is still wonderful.]
BubblePLY is a very cool annotation tool for online videos. It accepts more than just YouTube, but it makes no guarantees about those it will accept. I suppose you’ll just have to try it out and see.
BubblePLY enables you to put text annotations, subtitles, and even images and video on top of the video. This is a great tool for teachers. Imagine the benefits of being able to annotate instructional videos.
Here is a sample (though, not good one) from my personal video collection:
[edit – The embed doesn’t seem to work, which is unfortunate. I hope that they fix this. Here is the link to the video.]
Here is a screencast of the process done with Screenr. You’ll notice the audio isn’t very good. I think that’s my microphone (and/or audio card). Both BubblePLY and Screenr is a great job, though.