We use Camtasia Studio to create screencast videos, and I'm quite pleased with it. However at £80 for an educational licence it's not realistic to get licences for everyone who might just want to use it occasionaly.
CamStudio and ZDSoft's Screen Recorder have both been looked at here on Cakes as free alternatives, but the new free online service Screencast-O-Matic looks like it would be a better option for staff here to use.
Firstly it is online, meaning there are no issues getting it installed on people's computers.
Secondly it is even simpler to set up and use. You just need Java installed (the site will test this for you) and then to choose the basic settings.
I've created a quick training video if you'd like help using it - but you probably won't need help, because it is so simple. Go and have a play!