For screenshots, the extension allows you to choose the section of the screen you would like a image of. Once the image is taken there is then the option of using a variety of annotation tools and a variety of color options. The image then saves into the Snagit App library as well as into a folder labeled "TechSmith" in the Google Drive account.
The screencasting tool is in the Snagit App. By pressing the + symbol, a new recording will begin, giving you the option of recording the screen or a specific tab. Adjustments to audio can be made in the settings of the app. When finished, the recording can be uploaded to youtube and saved into the Google Drive account in the TechSmith folder.
To make Snagit work, you must install both the extension and the app from the Google Chrome Store. There are a few settings in your chrome browser that may need to be adjusted, which TechSmith does a great job explaining in the two video chops below. Original Hang Out from TechSmith announcing the new screen recording feature can be found HERE (15 minutes total viewing time).
Granted, if I am using my Windows 7 computer, I do have access to the snipping tool in the accessories folder for quick screenshots. The benefits of using the snagit extension over the snipping tool are the extra annotation tools to mark on the image with and the fact that it is automatically saved into a folder in my Google Drive. I use my Google Drive for a lot and this makes pulling in images easy.