That's a separate issue though. Screening a single physical DVD to a party of people simultaneously is illegal. But me connecting a really long cable to a DVD

That's a separate issue though. Screening a single physical DVD to a party of people simultaneously is illegal. But me connecting a really long cable to a DVD player and connecting it to my TV. There's no way that can be illegal. There is no A and B in your argument. There is 'A'. Connecting a DVD player to a TV using a cable.