Set up: we live in a Victorian maisonette - one below us is empty, we live in an upper one. Neighbours to the right - we speak to and are friendly, both flats. Neighbours to the left - downstairs were nice but have moved and property vacant, ones above with whom our bedroom and living room share a party wall have been consistently unfriendly for the 2 years we've lived here (think taking and signing for one Amazon parcel and denying all knowledge when asked for it later in the day). Odder still is when we had moved in after a couple of months asked us to stop turning on our kitchen light after midnight. It overlooks their kitchen which is completely protected by a frosted covering so we can't see in iyswim and from the layout of the flat it's unlikely if we turned a light on for half a minute once in the night it would be able to get into their bedroom.
A couple of months after we moved in we started getting to know people and just out of courtesy asked people if everything was ok as we keep late hours. Downstairs at the time neighbour said - actually it'd be great if you could smoke at the back of the house not the front as the couple of times a night you go out front, the door closing wakes me up. Everyone else fine - odd neighbours wouldn't speak to us.
Not to drip feed - our lights are on, but I watch TV on the laptop with headphones on and we don't listen to TV or music after 10pm because we want to not cause a problem!
I got an eyeful several times when getting a glass of water at 1 or 2 - I keep late hours - when you could tell through the protective screen that they were having marital relations in the kitchen with backlighting. I keep a bottle of squash in the bedroom now 
Aaaaaannyway, tonight, DH was playing acoustic guitar in the bedroom - late, about 11 - I could barely hear him in the next room. Odd neighbours banged on the wall - he immediately shut up and went to bed, I carried on listening to music on headphones.
For the last hour they appear to have been moving furniture around and screaming at each other. Haven't knocked on. I doubt it's someone moving in but noise levels are unbelieveable.
Should I ignore this or worry that something is going on?
Sorry for length.