Today, via Coolcatteacher in Twitter, I came across Screentoaster, a free online screencasting option with no need to download any apps to your computer.
They are still in Beta and you need an invitation code, which I got in my email immediately after I requested it.
It's very straightforward to record your screen there following the instructions. The audio you record after you've captured the screen, which feels a little awkward, but it's manageable after some practice. You can also add subtitles after having captured the screen.
Then, it's just a matter of publishing it and getting the embeddable code.
All in all, screentoaster is a nice free option to prepare tutorials, show specific collections of pages and adding voice comment.
In this first toasted screen above, I talked about a very nice Flickr post Cheryl Oakes sent to me. It can be very useful for our educational visual explorations.