Piracy is also a fine line. Take a game for example. As long as you own an iteration of it, then you can legally use an emulator to play it because you've already bought and own it. Maybe you bought Pokemon Blue on GB back in the day but now your system doesn't work (gee I wonder why) but the cartridge still works. You can legally play the emulator of it on your computer.
It's also a fine line where, some consoles are region locked while others aren't (looking at you Wii and DSi). I can legally play Tales of Hearts on my DSi because it's not a region locked console, and I can legally play the emulator of it with a translated Word doc up and read through the script that someone took the time to translate and I've saved.
Music, last I checked, is of a similar thread. So long as you own a physical copy of it - tape, CD, proof of buying the MP3 file - then you legally can transfer it to any thing else you own. CDs have taken the route to try and stop you from doing this- the Skyward Sword music disc that came with the game has a built in piracy blocker so you cannot easily rip of the music off. Rather that, you can rip it off, but you cannot then translate those files over to a MP3 player.
Which is dumb cause like, at some point, they won't make that CD anymore, and CDs will eventually wear out when you listen to them a billion and a half times. I'd rather take my chances in murdering the batteries of a cheap MP3 player.
Another problem with this system of streaming is what's happened on services like Netflix and Hulu. You've bought into streaming to watch on them, but the moment either stopped hosting Disney movies (the selection being few and far between anyway), I have less reason to have that service. Why pay for a service when I can stick in my DVD of said movie? Or worse, the streaming service doesn't have the movie that I have on VHS, but I want to watch it. But this pirated site DOES have it. Am I legally allowed to watch it because I own the physical thing, or am I legally allowed to use one of the many tools (some even for sale on stores like QVC) to just rip the old VHS content to the modern day computer?
And what about for movies that I don't "own" but were recorded to VHS when they were on TV, and were never released for people to buy? Like "Brink" the movie, has pretty much never seen an at-home release to watch. It's a fun movie and I have it on a VHS somewhere. Am I legally allowed to watch it? Yes, so long as I'm not charging at the door to come in and see it. That's where the clause of "private use" only comes in at the start of every movie.