If you are not using any custom design for your navigation menu:
1. Copy the YouTube embed code
2. In your thon event, navigate to the Webinfo Checklist > Front Page Customization
3. Under Custom Menu HTML, paste the embed code
4. Change the Width and Height to match your existing or preferred nav set up
5. Click Save
6. Go back to the Webinfo Checklist and click Publish This Event Now

If you have a custom coded template for your thon events:
The above is not best practice because this area is used to overwrite the left nav and customize on your own.  As a result, we suggest adding it as custom Javascript in the footer area.