Blockland has recording built-in.
not anymore...?
you guys can use Fraps. http://www.fraps.com/
Use fraps or w/e.
w/e?
If you don't want to buy Fraps, or don't want the watermark and a time limit on recording, I found a great screen recorder that actually has good quality. It's called Krut. It runs on Java so it work on most all operating systems, and is very simply and easy to use. http://krut.sourceforge.net/