It means that it's opaque to your ISP and other people on your network, which is at the very least useful for people using it at McDonald's or a university.

So, pretty much the opposite of all those people currently using it instead of going together to McDonald's or university?

On a more serious note, you would need to trust not one ISP if the video wasn't encrypted, but all the ISPs in the room simultaneously, and that is probably something even less trustworthy than Facebook.

well that means it's cryptographically superior to the ICQ client I used beginning of the century.

Unfortunately, the threats these days are also probably more sophisticated, and most people weren't using ICQ for sensitive business meetings.