Photo Credit: Angelina 🙂 via Compfight cc
While doing demonstrations on my MAC, either live or screencast, you want to draw attention to the part of the screen the viewer should be focusing on.
Mouselight
One way to do this is to use the mouselight app. It is $0.99 in the Mac App store. After installing you can use the shortcut key command esc to toggle between the spotlight on and off.
Scroll Zoom
I hold down the CONTROL (seriously, control not command) button on my keyboard and then scroll on the mouse/trackpad to zoom in.
If this does not work for you, you will want to turn on the settings. Click on the apple in the upper left hand corner and go to system preferences. Once there go to accessibility. Click on the Zoom icon on the left and checkbox “Use scroll gesture with modifier keys to zoom:”