Fair use

Fair use is a defence under section 107 of US copyright law, weighed on four factors: the purpose and character of your use, the nature of the original, how much of it you took, and the effect on the market for it. Use that adds commentary or meaning the original did not carry tends to help on the first factor, which is where most creator arguments live.

Two things creators get wrong. It is a defence rather than a permission, so it gets decided by a court after somebody sues, and no amount of credit, disclaimer or five-second rule creates it. It is also American. The UK's nearest equivalent is fair dealing, which is narrower, lists the permitted purposes, and does not stretch to most commentary channels.