Exactly what you need.
Ignore the 1 star reviews, odds are they dont have a 5s... Use this app to save where you place the slow-motion on your 5s slo-mo videos. Then send them wherever (Instagram, messages, etc) THIS APP DOES NOT FILM SLOW-MOTION, if youre buying it to do that, at least dont give it 1 star because of your stupidity.
TJSterrenberg about
SloMo Share! for iPhone - Share slow motion video to whatsapp, snapchat, Instagram, and eleswhere