If it’s filmed in public (ie openly in front of passersby etc.) you don’t need to get releases signed. I’m not sure of the specifics but for public events, releases would be a nightmarish complication. It’s assumed that if you appear naked in a busy street you accept the people will take photos.
For example, if you take photos of your family in a public place and post them online, there is no requirement to get releases signed by everyone caught in the background.
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