To add a video to your Brief in the Deck + Data format:
1) Go to My Briefs
2) Click "Edit Brief" next to your chosen Brief
3) Click "Video (Optional)"
4) Enter your Youtube video url
5) Click the checkbox confirming that the video is set to unlisted or public
If your Brief is in the Deck Only format, go to My Briefs and click “Create New Brief” on the top right, then select “Deck + Data”.