In the Video you can see that he unlock the Phone with his forefinger. 1)In 2:14 mins he show the Lockscreen. 2)Then he Unlock his Screen with his forefinger in 2:17. 3)For the "Exploit" he start Siri in the Lockscreen(2:23) with his !!Forefinger!! At this Time he unlock the Screen with his finger. So he can use the AppStore and other stuff. Therefore there is no bug or exploit. Greetz Dubbju
