Backstory: When moving to video in creative assets for advertisement, I've had trouble finding free videos to test. I've used unsplash for photos but there's nothing for video.
The Idea: Video platform for users to share and submit professional videos.
Deep Dive: You would build a marketplace for users to upload videos to a platform for customer to use for free. This would provide users a place to promote their work as well.
Validation: This works for unsplash!
Monetization: You would have to keep the platform free but sell ads targeted at video editors.