KLEE was a hoax. It would have been truly remarkable had it not been. Not only were the aliens receiving and rebroadcasting American TV signals, but they were also converting them from the American 525 line, 30 frames/ second format, to the (then) British 405 line, 25 frames per second system. If they could do that, they could have sent a message of their own in both formats.

But then maybe aliens are technically superb, but just no good at communicating.