Note: The ability to add stock video to a project is only available to Headliner Pro & Basic users.
Step 1: Click on the + sign in the Media timeline
Step 2: Click VIDEOS if it isn't selected
Step 3: Type in a keyword to search for videos
Step 4: Click SEARCH
Step 5: Hover over videos with your mouse to preview them
Step 6: Click on the video to select it
Step 7: Edit the length of the clip
Step 8: Click ADD TO VIDEO once you're done
For more info on editing your added video clips check out : How To Edit Added Video Clips