I love using Camtasia's baby brother Jing. The free version only records to swf with a brand but for $14.95usd a year you can also record in MPEG-4, unbranded. Both versions only record for 5 minutes, but was best for my 3d tutorials. I found camstudio to be poor quality (very pixelated when recording 3d screens such as poser or hexagon) and huge files sizes when I tried it. At least it's what I'm gonna use till I buy Camtasia.