As per your room size (in the video), do not buy too big speakers. Initially they look good to you. You can't utilize such a big size speakers in your room size. I urge you to get a Good amp , like the Denon you've chosen, but get small set of speakers..they too come in power..small doesn't mean tiny sound to you as it included a sub too. I had RTI A3 with RTI center and RTI A1 at rear..couldn't utilise those hefty speakers.
Amp should be more powerful than the speakers. Also after a few years those beefy speakers feels like .. your room need more space..it should be more clean and airy. But those speakers taken the space more than any humans in the room
Also those hefty speakers don't suit wall mounting and go against aesthetics (you will realize later)
Like some of the excellent small sets comes from Mission, Elac, Sonodyne, Energy, Cambridge audio, Magnet, polks etc.
Eventually the final decision is yours, this is what I feel after 10 long years with HT.