We've known how to efficiently broadcast TV programs to hundreds of millions of viewers simultaneously over satellite for decades now – in fact, that's how it all started :)
I wonder how hard it would be to add multicast capabilities to Starlink? Receivers could even cache popular content on a client side disk the way e.g. US satellite TV operators do for local ad insertion.
Good point about multicast - BT use it in the UK on their fibre/ADSL network to deliver live TV to their set-top boxes. I have never understood why it's not supported cross-ISP.
I believe it's very hard to implement across networks in a way that does not require core routers to become quite stateful and/or risks flooding parts of the network with multicast data nobody asked for.
There was a short conceptual revival of the multicast idea as an overlay network on top of unicast IP, under the banner of "content-addressable networks", but I haven't heard anything about that in a while.
I wonder how hard it would be to add multicast capabilities to Starlink? Receivers could even cache popular content on a client side disk the way e.g. US satellite TV operators do for local ad insertion.