You get the following error message:
This problem typically occurs if you use a USB display device to extend your display to a second monitor. This disables Quartz Extreme and will not allow Camtasia to start. It can also occur if you use a third-party program which turns off Quartz Extreme.
To re-enable Quartz Extreme, please disconnect USB display devices and restart your computer before launching Camtasia.
There is not a built-in control in OS X to re-enable Quartz Extreme, this is handled automatically by the system. There is a Terminal command you can use to re-enable Quartz Extreme if it has been disabled and restarting without USB displays does not turn it back on. You must be logged into an administrator account for this method to work properly.
Open the Terminal program in Applications/Utilities. Type (or copy/paste) the following command EXACTLY and press Return. You'll need to type in your administrator password and then immediately restart the computer.
sudo defaults write /Library/Preferences/com.apple.windowserver GLCompositor -dict tileHeight -int 256 tileWidth -int 256
Once your computer restarts, try launching Camtasia again.