Is this dlc worth something?

Everything is worth something to someone. I'm sure you can find a person playing that game.

If you don´t need it I would take it because I play the game. :)

so could I create private (on forum) giveaway with that? I don't want to get banned for that :)

This does not include the content of any dlc purchasable via steam,so you should not create a giveaway for it. You can however,simply open a topic and write the key there (so whoever is faster will get it),or create a little contest and give it to the winner(like a puzzle or 'post the best cat gif').