Yes, "Screencastomatic" sounds like a made up word, and it is, but we're going to be using it this year. Screencastomatic is a very easy and reliable screencasting tool. It is web-based, so it works on multiple platforms and does not require you to download any software. The free account allows you to create unlimited videos up to 15 minutes each with the ability to upload directly to YouTube or Screencastomatic.com for hosting. Think of it like this: when you want to show someone what's on your screen, you can take a screenshot, but Screencastomatic lets you add talking to it and creates a little video of what you want to show someone.
This video tutorial demonstrates how to use the free version.