It turns out the video was shot by a man named Billy at a beach named Billy!

Billy, of Sydney shot the video at a small cave at Billys Beach at Mystery Bay back in April 2013. And no, there is no connection with the name and how the beach came to get that name is whole other story.

Billy says his family are regular visitors to Narooma and the man featured in the video is actually his uncle. They stumbled upon the cave while exploring the coast and his uncle braved the swarm to check it out.

There was great hilarity as his uncle attempts to leave the cave only to be driven back inside by the massive swam of big, brown flies.

Not put off by the insects, they all plan to come back these summer holidays to enjoy the sights and sounds of Narooma, hopefully they pack the Aerogard.

So how exactly does a relatively obscure video shot at a small NSW coastal town go viral across the world?

Well Billy explained he first uploaded it to YouTube and then later made reference to it on the entertainment, social networking, and news website Reddit. It was from there that it started going viral and he was contacted by content distributor ViralHog, who on-sold the video to the Daily Mail. The video now has almost 140,000 views on YouTube.

And so what about the identity of mystery flying insects?

Well we have made some progress after contacting entomologists at the CSIRO and Australian Museum to try and identify the flies.

Also Ross Deutschbein contacted us after seeing our initial report saying he had seen a very similar insect behaviour around the Jervis Bay area possibly involving the same or a similar species of fly.

I have seen these flies or whatever they are up here as well, not in caves, but rock overhangs, always very close to the water, he said. There are always hundreds of them hanging upside down and mostly you can walk by with only one or two worrying you, they don't bite or sting but are as annoying as flies. Although they look and act like flies I have never seen flies congregate like this or just hang upside down.

Dr David Yeates, the director of the Australian National Insect Collection, thinks he has some idea of the identity of the flies based on both sets of footage.

They definitely are flies, I was thinking Coelopidae, otherwise known as kelp flies. There are some similar critters come up if you google images the family name, he said.

Entomologist Dan Bickel from the Australian Museum also had a look at Rosss photos and video. He said Coelopidae are a possibility if the caves are near the sea and they often occur in large numbers.

Well, that photo certain looks like true flies, Diptera: Empididae (Empidinae) danceflies but it is still a bit blurry I would love to get some specimens of this, he said.

So the only thing left is for this journalist, who actually lives at Mystery Bay, to head down to Billys Beach to see if the mystery flies are still there and to try and get a specimen of a few of the bugs for the entomologists.

Wish me luck and hopefully I too like Billys uncle can make my escape from the cave of doom!