You can then add the image to your message. The screenshot will then be placed on your Mac desktop. On a Mac, you can then select the area that you want for the screenshot so you can select the video for the screenshot.
HOW TO TAKE SCREENSHOT ON MAC WINDOWS 10 WINDOWS 7
You can also use the "Snipping Tool" with Windows 7 and 8.
HOW TO TAKE SCREENSHOT ON MAC WINDOWS 10 MANUAL
Check the manual the came with your laptop or device for specific instructions. Note: Certain laptops and other devices that lack a PrtScn key might use other key combinations, such as FN+Insert, to capture the screen. Save the image to your machine so you can add the image to your message. Open Microsoft Paint to paste in your image (Control + V) to crop, rotate, and resize the image.