Great video! Good to see people caring!
Smoothhounds will aggregate in large numbers, like a pack of dogs. This is why they are called hounds.
Another good way of telling the difference is by the tail shape. A Tope has a larger lower fork in the tail where as the Smoothies do not have a lower fork in their tail as well as a more pronounced rectangular notched cut out of lower section on the tail.
The Smoothhound's dorsal fin, when viewed from the side, is also set nearer to the pectoral fins than that on the Tope which is positioned more rearwards. The tail indentation on the Smoothound is less deep than that on the Tope, and the Smoothies lower tail lobe is small but on the Tope both upper and lower lobes are roughly equal in length.
Tope have more of a pointy snout as well.
The quick way to separate Smoothhound from small Tope is by the teeth, the Tope's teeth are triangular and ultra sharp capable of chopping prey clean through, whereas the Smoothound's teeth are flattened and blunt similar to a ray's and designed for crushing crabs and other crustaceans and are not designed for cutting.