Very cool capture, it's Euthyrhynchus floridanus(Florida Predatory Stink Bug) from a quick web search. The beetle it's feeding on is a Fuller Rose Weevil, a parthenogenetic pest of many garden plants.
@pwallis When I looked these guys up, I found some sources called it a beak and some called it a proboscis. I know it's gross, but fascinating at the same time.