My friend is kind of confused. Why wouldn't an observer outside of the event horizon see things falling into it? He says you can glean information from a thing that's outside of the horizon, but a thing falling into it should cease to be observable, at least by his understanding of black holes. My galaxy-sized brain understands this, of course, but my friend's pea-brain doesn't.
An observer outside the event horizon has to accelerate to avoid falling into the black hole itself and in the resulting frame of reference of this observer the horizon of the black hole coincides with future infinity and therefore everything falling into the black hole only reaches the event horizon infinitely far into the future. You can watch Leonard Suskind's lecture on that [1], falling into a black hole starts at about 53 minutes, but depending on your background you may want to start earlier, maybe even several lectures earlier. Looking at those Penrose diagrams is probably the easiest way to see what happens even if it will probably still not make intuitive sense.
So asking for a friend, ELI-aborted-CS-degree?