Like ima70 I am from Argentina too and we have looooads of legends and myths.

One of the most know is the "luz mala" which translates to bad light. It is also know as "el farol de mandinga" which is "the devils lantern". This legends is better known in Europe and the US as Will-o'-the-wisp.

The legend goes that where this light is seen where there is buried treasure and the light is the ghost of the owner thrying to keep away thieves. But anyone wating to unearth these treasures must beware as they are likely to be cursed.

Tradition states that on the 24th of August these lights are more visible because its St Bartholomew's day and the devil is free from the gaze of angels and can tempt greedy souls to these cursed treasures.

Now about the clip, I think is definitely staged, first of all the kids are filming themselves doing nothing, which is not uncommon with kids these days, but unlikely. Mobile phone contracts are  expensive in Argentina, more so outside the capital. So no one would waste it filming nothing. Second, the kids are not talking about anything in particular (though I am not an authority on country youth slang), and they do seem to be preparing for something. They are speaking almost on queue.

If you are interested on more argentine lore, I can tell you about the Yaciyarete and the Lobizon later.

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-'I curse the day my curiosity led me to investigate the strange stain inside
the atomic acelerator chamber'-
The Nuked Bug