barnstorm

brought a beaming Cowell and fellow judges Piers Morgan and Amanda Holden to their feet.

bring (one) to one's feet and bring something to its feet
to make someone or an audience rise up applauding or cheering in approval or in salute to someone or something. (Usually refers to an audience.)

gob·smacked /ˈgɔbsmækt US ˈgɑːb-/ adj BrE spoken informal
very surprised or shocked

barnstorm---
AmE to travel from place to place making short stops to give political speeches, theatre performances, or aircraft flying shows

a barnstorming audition on "Britain's Got Talent