How to update JS page information?

Question

JavaScript

I must say right away that this is not about Ajax. I'm making a browser extension that just looks for the video tag and style it. The bottom line is that the page does not initially have this video when it loads, and when I even call document.querySelectorAll('video') in the console, it shows that there is none (naturally, the video tag was already on the page). And another interesting fact, if you open the console, you won’t enter anything, but if after that you click on the arrow and select this video tag and write the same thing to the console again, then in response I will get the tag I need

Answer 1

Try this

Answer 2

if the extension is tailored for different pages, probably this is
https://developer.mozilla.org/en-US/docs/Web/API/M...