Actually, it's not unfeasible to be aligned to the receiver. From controls, it all has to do with the servo loop bandwidth. Using a camera chip and a laser, your sensor simply needs to sample the beam position within a millisecond and adjust piezoelectric or direct drive voice coil actuators to realign the beam to the center of the frame. Makes sense why they're (and who is) excited about this. The Navy would love to have high bandwidth wireless communication underwater while they're trying to scuba weld nuclear underwater basket mills. Additionally, this would find a lot of use in the depressurization chambers so the divers can stream Netflix as they try to avoid the bends.