Operating inside a stadium might not be the best thing to do. Especially if the crowd is in place. My Portuguese is not up to scratch so I have little idea of what actually happened but the hex looks out of control from the start of the video. Thankfully the stadium was not packed.
Castelão is one of the venues of the 2014 FIFA World Cup, which will be held in Brazil. The stadium was redeveloped for the tournament; the reconstruction project involved the addition of a larger roof, the construction of an underground car park with 4,200 spaces, and a new lower tier. After the redevelopment, the stadium now has an all-seater capacity of 66,700. The stadium closed on March 31, 2011 for the reconstruction project, which was officially completed in December 2012. Castelão was the first of 12 stadiums being built or redeveloped for the 2014 World Cup.
One wonders if this was a flight in preparation for 2014 operations. The only reason I am calling it as a hex is by counting the arms that I see. If anyone has more information I would love to hear it.