The individuals in all your scenarii have the right to express themselves under the first amendment. They can say what they like, regardless of who they team up with to say it.
If they spend money on making the video, and distribute it in a way that serves a political campaign, that money – not the speech – might be regarded as an illegal campaign contribution.
The Citizens United decision did not change the fact that corporations can’t donate to political campaigns, but it held that this kind of indirect spending couldn’t be counted as a donation. The “corporate personhood” argument was mentioned in the course of the shameless, flailing justification for this, but they could equally well have argued it was the speech of the individual filmmakers being suppressed. Except that would only protect the filmmakers, not the donors who funded the film.
Corporations don’t need rights of their own, because every actual mouth a corporation can speak from already has its own, individual right to free speech. “Corporate free speech” is a euphemism for the dubious claim that the First Amendment protects spending on propaganda in the same way that it protects speech itself. Because if that is true, there can be no meaningful limit on campaign spending.
