You present them to a human. Cory Doctorow has written some fiction about it lately. It's called Affordances I think.
Yep - you don't need to avoid false positives / false negatives, you just need to reduce the search space from watching 30 cameras' video feeds at once (impossible for 1 person) to watching these clips that have a high probability of being shoplifting (possible for 1 person).