I'm just finishing off a house where there were loose boards in every room. Why were they loose and squeaking? Because a heating guy had lifted them to notch the joists for new heating pipes ...not a good idea to drill or screw blind.
Plumbers! The wee rascals, aren't the pipes meant to go through the centre of a joist and not the top?
I wish tools like this guy would stop giving 'advice' they're always morons and need darwin awards at the ready.