So, the video I viewed that showed you how to crack Camtasia Studio 8 was deleted from YouTube, so unfortunately, I can't get that for you. However, I found this German (or whatever language that is) video on how to do it that seems pretty straight-forward right here: 

Remember to be very careful with this type of thing (scan all the files) and to block Camtasia's servers using firewall (easier than it sounds, but I forget how to do this.. I'm sure with a few searches in Google, you'll figure it out).

It does have a 30-day free trial, though, so you may not even want to do any of this.

Good luck! :3