Does anyone know if that glitch where you can use a browser in YouTube still works ?

If not is there another way

Not sure what you mean.

The 3DS already has a browser (I still think they should have called it the Web Bowser)
or do you mean the Youtube App ? Is there a way to glitch the app into viewing or installing a different browser? Beats me.

The OG 3DS's browser is pretty much useless.
The New 3DS's browser is a lot better, but not great... If you weren't aware, on New 3DS, you can watch youtube through the browser (no app needed), and it's much better this way, as you don't even have to close your game to watch a video.