YouTube-like scroll down in fullscreen mode

**Is your feature request related to a usage problem (not a bug)? Please describe.**
No.

**Describe the solution you'd like to see implemented**
On YouTube, you can scroll down from a video, even when it is in fullscreen. It remains in fullscreen, and you can scroll back up to have the video display like normal fullscreen. This would make it easier to quickly look into the description, or into the comments, without the need to close fullscreen. This probably requires some heavier tweaking in the page and videoplayer structure.

**Screenshots**
Example of how it looks when you scroll down in fullscreen