Exactly.
There is a rule called ‘fair use’ that says that teachers may show or edit scenes from movies for their students without breaking copyright laws.
But if you get that scene by ripping it from a DVD, you have broken other laws becaus eyou ‘cracked’ the protection code on the DVD.
Another rule is this: if someone else wrote/filmed/drew/painted something, you cannot use it without their permission.
But if someone told or learned you a concept or a special effect trick, and you retell someone else in your own words, using your own images, you can use it:
There is no copyright on “the idea” itself.
So don’t Copy->Paste your tutorials, and you’re fine 😉