And VCRs too. The original Macrovision technique relied on the low tolerance to noise in the old record-mode AGC circuits on first generation VCRs. But when VCRs improved to the point that Macrovision was ineffective, legislation was passed so that VCR manufactures had to include a special circuit to recognize the Macrovision noise bursts, and emulate the old behavior. (Source: my memory of an old article in an electronics magazine, so the above may be somewhat inaccurate -- the article may have been only referring to proposed legislation, or possibly industry self-regulation).

It would have to get a lot nicer. I work in film and shooting an image of a TV or computer monitor is often a pain, even with high-end cameras, due to interference between the frame rates of the camera and display devices, as well as light intensity. For high quality results the typical workaround is to just throw up a grid pattern on the screen in question and composite in the desired image afterwards.

Is it possible to get results this way, yes of course. Are the results any good, not really. Commercial pirates work with people in the exhibition sector, amateurs rely on known weaknesses in popular disc formats. You'd have to be pretty desperate to rely on streamed media as your 'original.'