Recording a lesson can be done by several ways:

iPhone records pretty well but video size is limited to 4GB or around 50 min at maximum resolution. You will make better videos with a iPhone mount and a microphone. CNet UK has a good review on movie making with iPhones.

Olympus LS20 (£280) is a superb HD video and audio recording device. With a microphone such as this (£49) one can record lectures in a classroom. Again file size is limted to 4 GB per file.

One can use iPad (£400) as a whiteboard and record (audio only) using apps such as ‘explain everything‘ or ‘screenchomp‘. Screenchomp is available for free but explain everything is a paid app (£2.49). Video can be recorded using device such as moviemount. It is good to have a stylus to write on iPads. I have a adonit jot pro stylus (£30). Styluses are reviewed here and you can know more about screencasting here.

Because I use camtasia studio to edit my screencasts, I am not so much informative about video editing softwares. I would like to hear more about it.

Olympus sounds cheaper. I would love to hear more about it.