The area is a couple of roofs, one big one little. There was some old chalk and signs of cleaning so I’d imagine these of similar lines have been done by others before me and Ben Pritch.
Just watched the clip an if it's where I think it is (and I think it is) then this problem needs continued attention or it will rapidly return to a very green state. Also, much as I hate to do this, you might not have done the FA....Good name though, very apt.