To grab a photo first ensure the you have installed the Nimbus plugin or somthing compatible. Copy and paste this link into your chrome browser:

https://chrome.google.com/webstore/detail/nimbus-screenshot-screen/bpconcjcammlapcogcnnelfmaeghhagj?hl=en-US

Once installed the nimbus icon will appear on the upper right. At anytime during your video meeting, click the icon. It will present a menu. Select "capture fragment" and hover over the remote parties video. When ready depress your mouse wheel or tap your mouse pad. 

This will prompt you to save the capture picture.