Ah yes, the sacred grass boxes! Magnus has clearly established his outdoor surveillance station. The chattering is peak cat frustration - "THOSE ARE MY BIRDS IN MY YARD AND I CANNOT REACH THEM!"
The territorial marking around your space is the ultimate cat compliment though. You're not just his human, you're part of his claimed kingdom. Every corner scent-marked is basically him saying "This is MINE and so are YOU."
That feral background really shows - he's running full security protocols on his domain. Indoor life but outdoor instincts never switched off!