The car is knocking at the right rear area
Take a look at the right/rear tire tread. See any weird wear patterns on the tire tread? If that’s ok, remove everything including the spare tire and jack from the trunk, and see if that stops the noise. If you still haven’t figured it out after that, it may be a problem with the rear suspension system. You’ll need to get a shop to put the car on a lift and have the suspension inspected.
Could be wheel bearing, shock, bad muffler clamp. My internet eyes cannot see anything from here, do you want to try and figure it out, or just take it to a mechanic?
Does it sound like a bunch of 2x4’s in the trunk? Bad shock absorber upper mount bushings.
Bad stabilizer end links makes a knocking sound. The Focus is using old style stabilizer end links in the rear with the rods and bushings
I have been getting a knock from the rear on my 56 plate focus 2.0 tdci. Check the trail arm bushes as they are a common complaint on them. Not an expensive fix at £42 for both sides from Ford but can be a bugger to fit them