Vidosic was impressed by Berisha's ability when he was in Germany to watch his son, Qantas Socceroo midfielder Dario Vidosic, play for the then German second division club.
"Rado had a good look at him in Germany and said he thought he'd fit in to our system of play," Postecoglou said.
"He's at the right age and we think he has plenty to offer.
"Bersart is eager to get here and start working with the club and that's also very encouraging."
Berisha has been capped 17 times by Albania and played UEFA Champions League football with Hamburg and in 2006 became the first Albanian to score in the group stages of the competition.
He is now awaiting his work visa in Germany, but is excited by the prospect of continuing his career in Australia.
"I'm very happy to sign for Brisbane," Berisha said. "For me it is a new challenge and I'm very happy to take the challenge.
"I've never been to Australia but each time I heard about the country, I heard good things.
"I know the football in Australia is very strong now.
"Football has improved a lot and it is now at a very good level."