[lisper]

IANA physicist, but I have a pretty good intuitive understanding of relativity. Yes, light paths are reversible. The reason you can't get a beam of light out of a black hole by reflecting an incoming beam is that from the point of view of an observer outside the event horizon, and inbound beam never makes it past the horizon inbound because of time dilation. At the horizon, time stops (relative to frames of reference outside the hole).