Microsoft Expression Encoder 4 allows you to record your PC’s screen for video training and demos. This software comes in two editions, a free and pro version. The main differences is that the free version only lets you record for about 10 minutes, and only supports a limited set of CODECs to export your video.
If you're only going to post your videos to sites like YouTube, most people are limited to 10 minutes uploads. After you finished recording your video the software also includes tools for performing simple edits and overlays.