Is this a "Ropen' pterosaur hunting for fish off a Papua
New Guinea beach as an amateur videographer thinks?
According to Jim Blume and David Woetzel, The Ropen or "demon flyer"--a monstrous creature that's terrified the natives of Papua New Guinea for thousands of years--is real.
Another smaller creature, the Duah, is possibly related to the Ropen; this creature haunts some of the far flung outlying islands.
Jim Blume and David Woetzel are two daring researchers that have explored the dangerous regions--including the treacherous outlying islands--where the prehistoric monsters are known to hunt their prey.
The descriptions of both monsters match that of fabled pterosaurs--ferocious flying relatives to the dinosaurs thought to be extinct for 65 million years.
The creatures first came to the attention of missionaries who described
these nocturnal fliers as having large creatures with bat-like wings,
that were connected to an elongated beak. They described razor sharp
teeth, muscular tearing claws and a very long whip-like tail with a
split or flange on the end.
There are reports from both investigators and natives of these creatures glowing in the dark. Researcher David Woetzel called the phenomenon 'Ropen light', he spent time studying them and even recorded images with his video camera. 
Other than actual modern-day sightings of the two, a surviving 16th Century maritime chart lends credence to the hypothesis of two distinctly different creatures.Two daylight videos and the entire Helium article may be found here.
The 1595 chart cautions sailors about "sea monsters' and depicts various coastal regions of Earth where monsters might be found. In the area of Papua New Guinea, two 'sea monsters' are illustrated: one is much larger than the other, yet both have almost identical physical traits. Each have long necks, prominent head crests, tails ending with a flipper like appendage and ridges along their backs. They are shown flying above an island. 
Citations and other links
 'Ropen Light' Sighting by David Woetzel
 'A Pictorial History of Sea Monsters,' Sweeney, James B. 1972, p. 42.