Pornography and sex are different things, with different laws regulating them. Videos of children (i.e anyone under 18) having sex are illegal in the vast majority of countries, irrespective of the age of consent.

A sign of how times have changed from the crazy world of puritanism (when oral intercourse could be considered illegal) - you assume it is the clip that is legal. They're talking about the oral sex when they're referring to legality.

It is, of course, obvious that distributing a video of a legal act can be illegal. For instance, there's the obvious thing that a 14 year old is legally allowed to masturbate. They are not then allowed to video themselves masturbating and then distribute the video.

Does a 14 year old truly understand the gravity of the acts of filming and distribution here? I would argue against, and for that reason I find it hard to understand how courts could agree to the punishment when the agent of the crime is so obviously incompetent.

No, doing and distributing a video of it are completely different things. There's nothing wrong with children being naked to take a shower, for example, but distributing a video of naked children showering is completely different territory.

I'd argue that intend and who it's shared with that matters a lot. A nudist family's holiday pictures might be harmless when it stays in the family, but turn into child porn when it ends up on sex sites.

In general, I'd say that distributing any sex act involving someone else, without the consent of that other person, who needs to be adult enough to be able to give that consent, should be illegal.

Because the child porn laws are federal, and have a hard age limit of 18.