Wow my memory is bad - I’d forgotten I had seen them live until I read this. I had to look up their tour history to figure out that it must have been the Momentary Lapse of Reason tour. Listening to their albums now I much prefer the earlier stuff, but they still put on a good show in '88.
Once an end-to-end, encrypted, connection is established between a pair of peers then anything can be sent through it. The establishment proces is generally facilitated by a server of some description so neither peer needs to allow inbound connections. (I’m a long, long way from being an expert on this and happy to be corrected - but this seems like network fundamentals?)