If everybody pirated their videos, maybe media companies would get a clue and make a better product. Nobody pirates music anymore—it is much easier to just pay a small amount to Spotify and the like and get access to almost any song you’d want on basically all your devices.
If anything, perhaps it is more ethical to hard pirate video than it is to let media companies shoot them selves in the foot...
People would stop producing content because there's no money in it. So yeah, it's harmful.
The demand for the fundamental content would remain and if some suppliers are unwilling to provide for the demand, other suppliers would arise.
Music piracy was a huge problem in the 90s, and from what I can tell, that's essentially disappeared with iTunes and Spotify. It should be easy to buy exactly what you want for a reasonable price.
From what I can tell, movie and TV show piracy went way down in areas where Netflix was available, so what does Hollywood do? They lock down their content even more and reduce the content available at any given service.
That's backwards. They have a winning service, they should double down on it and make more content available. Maybe distribute new releases to Netflix customers that have a premium account or something, and have a payment tier with nearly complete access to old content with a single subscription. That's essentially what Spotify does, and it works.