Staffordshire Police say the youths were at the shopping centre on April 26-the same day rocks were thrown at shoppers and staff. Officers now want to talk to the teenagers in the clip, Birmingham Live reports. The video shows the youngsters surrounding a security guard on a bridge at the site, with several of them appearing to film the exchange on their mobile phones. The clip then sees the guard repeatedly ask the boys to" leave the site" as one of them exclaims" we've left the site" before ki