Selenium - How to test fullscreen video player?

I'm trying to write a selenium test in Java to test the controls of a video player in fullscreen mode (ie. play/pause, volume, etc). However, once I open the video in fullscreen selenium is unable to interact with the id's of the elements (video control bar) that I am trying to manipulate.

For reference, I have already written a test that tests the video player and controls while not in fullscreen mode, which works. I have also tried to check whether perhaps a new window is opened when entering fullscreen, but this is not the case.

Does anyone have an idea of how I might get Selenium to interact with the fullscreen player?

Thanks