I use something call Jing. It allows you to copy only what you want on the screen, as well as make a video of your screen (audio too if you want!).
I've actually used Jing (by TechSmith) as well. Great tool, and I love the $15 (I think) Pro version per year - to do screen casts, adding your own voice over content and hosting. I think Jing will even let you save your screencasts to YouTube directly. Completely agree. Thanks for the tip! Do you know if there's a mobile or iPad version of Jing?