Does that video show the connection used to display that.

If not, I'm guessing that example case is either using a lossy data compression or multiple cables running to multiple displays.

Lossy Data Compression is used on the Pro Display XDR and Apple doesn't seem to lose any sleep over it. DSC is quite good.

There's also the fact that nearly all content has compression as part of its path to display anyway. Video & images are obvious examples, but also GPUs almost always render to a lossy compressed framebuffer as well. It just saves way too much memory bandwidth not to do.

So as long as 'transcoding' from GPU framebuffer compression to DSC is itself a mostly lossless process, there's realistically not even a quality hit from it anyway