Rather than just a deletions page, have a "quality decrease" page which is much more aggressive about which videos are included, which drastically lowers the quality of the video to take up 5x-10x less space.
If someone is upset about the quality loss, they are free to re-upload the video, which replaces the low quality version with standard quality again and resets the timer on decreasing its quality again for a few months. Or people can email you about things they really care about to get added to an exceptions list which is never reduced in quality.