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.'
Unless the playback hardware is DRM'd and encased in an impenetrable box, you don't need to capture photons and compression waves, just the output at the DAC, which can give you perfect fidelity to the original digital signal.
Yes, but who does that in real life outside the tiny community of extreme hardware nerds? Absolutely such things are possible, but they're increasingly impractical. It's the same reason that people promote widespread adoption of encryption; there's no encryption so strong that it couldn't be easily circumvented at the endpoints by really dedicated sppoks, but the sheer inconvenience is itself a safeguard against mass surveillance.
As for the spooks, depends on what you mean by "easily".
Edit:
According to a video[1] posted on Vimeo (which claims to be from a DMCA hearing) representatives of the MPAA appear to make recommendations on how to do the capture and they provide some tips that will increase the quality of the final product.
For example, hooking directly into the audio output; and, removing other light sources.
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.'