You can insert a video from YouTube or Vimeo using an Iframe block in the Slides editor.
- Copy the iframe embed code from the video's sharing options.
- Add an Iframe block to your presentation.
- Paste the embed code into the block's source field.


Example Vimeo embed code:
<iframe src="//player.vimeo.com/video/93361282" width="500" height="313" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>