OK, I admit I don’t know much about video compression. So what does my TV receives from Netflix if it’s not pixels? And when my TV does “upsampling” (according to the marketing) what does it do exactly?
It receives information about the spacial frequency content of the image. If you're unfamiliar, it's definitely worth looking into the specifics of how this works, as it's quite impressive! Here's a few relevant Wikipedia articles, and a Computerphile video:
