As outlined in the video, it's a way for Edge to manage the tabs and extensions opened and make sure it's stable and work the way it's supposed to. This technique is also used by other browsers – it's just how Edge is designed.
You can provide feedback to the dev team so they further improve Edge by pressing Alt + Shift + I. Any new features and change to Edge will be sent via a notification at the upper right corner of the window, and you can update it any time they're available.