(credit for the link: nggarmy on reddit)It just means if you want to watch him practice you have to be escorted from the media room. He's not actually practising among us!
He'll also be practising for more than 15 minutes but media will only be allowed to watch for 15 mins. Don't panic!
There's a reason journos aren't supposed to tweet press notices. The press conference schedule is on a different screen.