Hunter camouflaged while mounted - without a buff?

[mist3h]

Hello everyone

I really hope I'm not making a complete fool out of myself with this post :3

Yesterday I ran into this guy in Orgrimmar, sitting on his flying mount while in camouflage (It was definately the camouflage mechanic visually), but he did not have the buff - or any other buff that could explain it.
The camouflage never ran out and he changed mounts several times before flying away.
I asked him countless times how he did it, but he pretty much ignored me. Until I offered him gold. I said "everybody has a price" - his turned out to be 10k gold.
While I'd prefer not to pay him 10k gold, I genuinely can't find any information on this "trick" anywhere(I am pretty sure it's not something working as intended).
And I really really hate being kept in the dark about something like this.
But first I'd like to ask if someone could potentially save me from this expense (which is big to me)?

For some stupid reason I did not take a screenshot of it - I actually didn't even think of it before he was gone.
But I know his character name and I'm planning to stalk the shit out of him

Any tips?

[plagueware]

It's a hack you can find it on youtube.