When you're using the document editor, adding a video to a document that you're working on is simple and easy!
You'll start by clicking the cursor in the space where you want the video to go, and then hitting Enter on your keyboard to start a new paragraph. You'll see a menu bar pop up. The video icon is the second icon from the left. Click that icon, and copy and paste the URL of the video you want to include in your document. Click OK, and your video will appear!