[header] How to screenshare (screencast) on google + hangouts [title] Open up the hangout you'd like to run the screencast in. [title] Hover over the picture in the center of the screen. [step] If you are the only person in the room at the time, you'll see a black screen; hover over the black screen instead. 
[title] Look and click on the green computer icon. [step] It has an arrow shooting out of it from the left hand toolbar to the page.