Dubai-based broadcasting company MBC Group announced today it has signed a major new deal with giant Warner Bros to show all its US TV shows for the next two years.    MBC will debut Warner Bros International Television Distribution (WBITD) series in the region on free TV, at the same time as the US broadcast of the programmes, officials said.    MBC Group was established in 1991 as the first pan-Arab free-to-air satellite broadcasting company in the Arab World.