Is it legal to make an AI video of someone?
Making an AI video of yourself is fine, making one of another adult who agreed to it is generally fine, and making one of someone who did not agree ranges from a platform violation to a criminal offence depending on who they are and where you are.
The lines that are clear everywhere
Never a child. There is no jurisdiction and no context in which generating video of a minor from their photo is acceptable, and no app should let you.
Never sexual content of a real person without their explicit agreement. A growing number of countries now treat this as a criminal offence specifically, rather than as a civil matter.
Never a real person saying or doing something intended to be believed. That is where the word deepfake earns its reputation and where the serious legislation is aimed.
Public figures are harder, not easier
The instinct that a public figure is fair game gets it backwards. Many jurisdictions give them a specific commercial right in their own likeness, and the reputational damage from a convincing fake is exactly what that right protects.
Parody and commentary have real protection in some countries and much less in others, and a video that travels does not stay in the country it was made in.
The practical test
Would you show this to the person in it? If the honest answer is no, the legal question is probably not the one you should be asking.
Ask before you generate rather than after. Consent given after the fact does not undo the generation, and on a shared phone it does not undo the copy in the camera roll either.
Do not expect the app to stop you
Automated screening in these tools looks for unsafe content — nudity, gore, hate symbols, illegal activity. It is a content filter, and it is good at what it does.
It is not a consent check. It does not know who is in the photo or whether they agreed, and no current tool can tell you that. The judgement is yours, it happens before you upload, and a green light from the app is not an answer to it.