The stuff in the middle of the screen: blue squares, progress bars, the red progress bars… that’s a weakaura setup.
Everything else appears to be ElvUI which is a popular full ui replacement.
I am not familiar ElvUI but I am with weakauras. You can do a lot with WA, but it’s like getting a bag full of mixed Legos and no instruction manual: you’re supposed to use your own imagination. This can make it very daunting for a new user
You can however use weak aura setups other people have made, very easily.
Check out
https://wago.io/weakauras/classes/death-knight
and
https://www.weakauras.online/en
- Find one you like
- click the copy import link on the website
- in game, log in as your character and open weakauras (/wa is it’s chat command)
- Click the New page and click Import
- Ctrl-V to paste what you copied from the webpage
Make sure you select a weakaura that is for Battle For Azeroth. Classes changed significantly and nothing from legion (which your YouTube showed) will work anymore. Ideally you want a WA updated in the last 6 months. Like all add-ons Weakauras uses the api’s Blizz has created and those have changed many times since bfa was released and all add-ons, including Weakauras, have to update themselves to keep working. Some WA changes also changed the data which represent all the icons, etc… behind the scenes.