Most of the responsibility lands on William's shoulders, because it's his IQ that dropped a couple of points when he was around them. Although, his friends didn't help him in the situation either. If I was his friend, I would've made sure things settled down a bit, because I would know we're being filmed. Too much caution was thrown to the wind.
They're all good old friends, but the friends can do as they please personally. They're not the future King. They won't take the heat for anything...William will. Friends look after friends, imo.