The same reason there are illustrations that appear on screen and there's music in the background. Fundamentally, it's a boring topic (we moved our menus around). So they spiced it up with some things that create interest.
Probably to make it feel like the video is being filmed through Snapchat :)
The high-pitch noise in the background was what I noticed the most. I have nothing against the "behind the scenes" style, but at least don't hurt my ears.
Next update's gonna be the filming of the filming of a filming session.