To add a video as a slide in your lesson (not as a component), click +Add and then Video.
There are several ways to add a video to your lesson:
Search in LessonUp: use a video from the lesson library.
Search the web: find a video on YouTube or Vimeo.
Paste a link: if you already have the link of the video, paste it into the input field.
When you click add, the video is added as a slide in your lesson. You cannot resize or drag the video.
If you do want to resize or drag the video, choose +Component --> Video. It will look like this: