three modes: 1 - immediate life threatening danger, call police (and notify friends/family) 2 - non-immediate, but still notify friends/family 3 - possible danger (just scared) - record everything (remote server), hold for 24 hours before sending to friends/family.
I think #3 could be one of your best use cases: A lot of people don't like walking to their car alone at night, or through a dark alley, or meeting someone on a first date. But they also don't want to stream that to their friends/family for no real reason. This gives them time to stop/erase content where nothing happens. In the case where something does happen, evidence is still maintained even if the phone is knocked/dropped out of their hand immediately, or whatever. You could also have a quicker way to "upgrade" to #1 in this mode, in case the threat turns more immediate and the user still has time/thought process to act.