I think you just click on the icon that looks like a film strip, or a cinderblock, the one right next to the icon for a picture, which you click on to upload a picture. I know the Upload Video icon allows us to insert a link to a video that is online, like one in YouTube. This is how it comes up when you click on it:
Embed Video
Paste the appropriate Video URL or Embed code below
YouTube and Vimeo are supported
and there is a space to put in the link or code. See if that works for you.