Bing found the following results
Add Google files, videos, website content and more - Sites Help
How to upload your video to Google Sites - YouTube
How to Upload Video in Google sites (EASY) - YouTube
How to Use Videos in Google Sites - YouTube
How to embed content from the web to your Google Site
Google Sites Tutorial - 06. Video
Add a Video Using Google Sites - TechnoKids Blog
How to Use Google Sites - How-To Geek
The Ultimate Google Sites Tutorial [20+ Templates & Examples]
ELM 300 Creating Your ePortfolio: Uploading Video to Google Sites