Nice and simple. Thanks for sharing.
I experimented with something similar a while ago. Video inside of text, over a background video.
I even started a tutorial but never found the time to finish it and eventually forgot about it
I even tried to make this tutorial some 5 months ago but whenever I started recording some disturbance came over than finally on 29 January I decided to make another tutorial to start my new channel. And today I Finally made this tutorial.