HI Dary, I’ve just changed the from and rear pads on my RS4 B9.5. The videos for the S4 you have found online can be referenced for your model mate. I used the same and can confirm the S4 replacement procedure is exactly the same. I went for the Brembo pads rather than OEM, feel pretty good so far.
if you are ordering replacement pads, make sure you get the accessories kit, it contains new clips etc. The old clips on my pads came out in pieces and they will need replaced. I also purchased new pad wear sensors. One sensor for each axle.
Im sure you have this in hand but just a reminder you will need an OBD2 to retract the rear handbrake before replacing the rear disc and pads.
Edit, sorry, just realised you posted this 8 months ago! Im new to the forum but lesson learned, check the dates before replying. 🙂