Why should the law care about what I do behind closed doors?

The law shouldn't care (if you are a law abiding citizen) about who you take into the bedroom as long as they are consenting adults. How many guns you own. What you eat for supper. What kind of TV shows you watch. Whether you watch porn or not.

You can stand on a public sidewalk and take pictures of my house. You can't walk into my house uninvited and start taking pictures.

Society sets laws announcing those actions that it deems unacceptable in polite society. If evidence appears that causes a reasonable person to suspect that illegal activity is going on, society should investigate. Of course society might find itself having to jump through hoops by adhering to constitutional law. It cannot just invade your personal space and demand to know what you're up to just because they don't like you.

Are there any free methods to remove only the vocals (not music) from an MP4 file?

Liberty is not boundless. It does have its limits.

If evidence arises that you are doing these things behind closed doors, don't you think the government has a moral obligation to investigate?

The law doesn't care about what you do behind closed doors as long as it is within the bounds of what the law allows.

What is price of the "liberal celebrities" e.g. Bill Maher, Seth Meyers, Jon Stewart, Trevor Noah, Jimmy Kimmel, Desi Lydic etc. to join the great MAGA movement like Stephen Colbert who wanted to European ambassadorship to turn back on "the Left"?

It shouldn't to a point.

But what if you're raping little girls behind closed doors? Killing gay men? Watching child porn?

Your speech is free. But if it causes malicious harm to someone, you can be sued.

I've been listening to subliminals for 3 days. 5 videos before sleeping and after waking up. My left ear started hurting relatively bad. Is there an explanation or should I go to a doctor?