PiP doesn't automatically start when switching between desktop screens.
Steps to reproduce (scenario 1):
- Open Orion and maximise the window. Start a YouTube video in a tab.
- Don't switch tabs. While the video is playing switch to another desktop screen (for example, by swiping left/right with three fingers or Ctrl + left/right arrows).
- The playing video continues playing in the background but doesn't switch to Picture in Picture.

Steps to reproduce (scenario 2):
- Open Orion and maximise the window. Start a YouTube video in a tab.
- Switch tabs. Picture in Picture kicks in.
- While the video is playing switch to another desktop screen (for example, by swiping left/right with three fingers or Ctrl + left/right arrows).
- The Picture in Picture moves across to the other screens.

If a video is playing, and that tab goes out of visibility (whether that's due to switching to another tab, or moving across screens), Picture in Picture should kick in.
Version 0.99.134-beta (WebKit 622.1.9.19.2)
Sequoia (15)