With the recent macOS Catalina update, we can now finally use the picture-in-picture mode while watching videos in Safari in just a few clicks. Meaning you can keep doing what you’re doing while still watching videos from websites like YouTube, Facebook, and the likes.
To enable the picture-in-picture mode, you can either right-click or hold the ctrl (control) button and left click the volume icon and then select the Enter Picture in Picture option.
This is how picture-in-picture looks like:
The video box is persistent, it floats on top and it will follow you to any workspace you go.