urx unit loader Justin Bieber, Miley Cyrus perform together; New York still standing
justin bieber boyz ii men Justin Bieber, Miley Cyrus perform together; New York still standingNow we know why Justin Bieber briefly encouraged fans to storm Madison Square Garden on Tuesday: His show featured a boatload of special guests.

The MSG show was filmed for the 3-D concert movie/biopic Jon Chu (“Step Up 3-D”) is directing, and as befits a big-screen extravaganza, it featured a lot of cameos. Justin’s mentors Usher and Ludacris were there, and so was Sean Kingston. Boyz II Men — whose biggest albums were released before Bieber was born — got in on the act as well (that’s them above with Justin).

]]>Miley Cyrus, who joined Justin for a duet on his song “Overboard.” Which also describes the reaction of the crowd every time Miley and Justin got within three feet of one another. A snippet of their duet — filmed from a section high above the stage — is below. You can hear the screams rise up when the two teens get close. Bieber: The Movie is scheduled for release next year. Follow Zap2it and Zap2itRick on Twitter and Zap2it on Facebook for the latest TV, movie and celebrity news. Photo credit: Getty Images