Is this one of you??

[GoatSucker]

well pictures are copyrighted and someone somewhere had put a lot of work into that " poster" (so yes it is the same thing)

No, it's not. You're confusing selling a tangible item, with mass duplicating a non-tangible item (the artwork / the music).

If you a selling a single poster, you are selling the physical item. But if you were to print a 100 copies of that poster, and sell each of them, you're talking about copyright infringement.

Same with the gig. If by chance, you were given a promo version of that gig on CD, you would be allowed to sell that single promo copy. But you can't possibly believe that duplicating that CD several times and selling copies of it is the same, morally or legally.

Just because you received the download for free, and it didn't come with a several page long license, doesn't mean that you have been given the right to do what you please with it. In fact, copyright law states that unless you have been given special rights by the copyright holder, you can't do shit with it. End of story.