Note - Your video must be uploaded to YouTube or Vimeo in order to be attached
#1 - Go to your listings section
Go to your listings via "Manage Listings" tab at the top of your backend, then click on "Listings".
#2 - Find the Listing you want to add a video to and click on "Attach"
#3 - Paste & Link
Depending on where your video is hosted, go to the "Youtube Video" or "Vimeo Video" tab. Now you can copy-paste your link in the box, and click on the blue button to link the video.
#4 - Verify!
Verify the video preview frame is below the field! If not, check the URL first. If the URL is valid, make sure the Youtube video settings are set to allow embedding on 3rd party frames.