They 100% need a warrant if the owner of such footage doesn’t want to voluntarily hand it over. Most people generally voluntarily help out when it’s clear the footage is of value, often calling the police proactively to hand over footage. But if they don’t want to release the footage then they’re under no obligation to do so without a court order.

They ask and everybody turns the footage over. They need nothing at all to ask for the footage, it just takes a large amount of man hours and ends up producing grainy, low-res footage. Everybody knows how important video footage is, so the real issue does seem to be that Flock makes it too easy?