The best thing about this video is the way it turns your expectation of shark-as-predator on its head. When a lot of us think about sharks, we imagine them as the animals that do the eating, not the ones getting eaten. In reality, different species of sharks exist across a range of ocean ecosystems, and can occupy any number of positions within a given food web. In habitats like Florida's shallow coastal waters, big groupers are known to prey on blacktip sharks. That videos similar to the one above exist – like the one featured below, from 2007 – suggests groupers may feed opportunistically on caught sharks with some regularity:
According to the Florida Fish and Wildlife Conservation Commission, blacktip sharks are a common catch among coastal sportfishers. The IUCN notes this as well, specifying that the species is fished for and targeted in recreational and commercial fisheries alike, but adds that the species is "near threatened" and "highly vulnerable to fishing pressure," so it may not be an ideal species for sportfishing.