is it correct to say " CAUTION : PLEASE DO NOT WATCH IT IF YOU'RE NOT INTERESTED IN JET PLANES. "
A "caution" should be used if there is a risk of injury or damage. No one will be damaged by being bored. I would not use it.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.