Panther, No. Melanistic mountain lion is possible. Melanism occurs in many animal species. Hard to get a grasp on the size from that video.
And just what is the difference between a black panther and a black mountain lion?
As far as I can find there has never been a panther in North America except in zoos. We have mountain lions, and occasionally Jaguars along with the smaller cats.
"Black panthers live chiefly in the hot, dense tropical rainforests of South and Southeast Asia. They are mainly in Southwestern China,
Burma, Nepal, Southern India, Indonesia, and the southern part of Malaysia. Black leopards are more common than light-colored leopards.
Part of the necessity for scientific nomenclature is the generalized or common use of generic names being applied to multiple animals. "Panther" is one of those names as applied to mountain lions.
Puma concolor historically has been called many things including cougar, Mexican lion, mountain lion, deer tiger, mountain screamer, puma, painter, catamount, Panther, Silver lion, Devil cat, Indian devil, Sneak cat, king cat, mountain devil, red tiger, Deercat, Fire cat, Plain lion , Grey lion, lion, Caracajou, Klandagi, Catawampus, Quinquajou, Long Tail, and Swamp lion.