Didn't hear the bloke speak so I can't comment on him specifically, but US television seem to subtitle a lot of english speakers that I can understand perfectly.
When I go to the states (I have a reasonably clear, non-regional english accent) I quite often have to repeat myself.
I have heard that when 'The Office' is broadcast in the US that the Gareth character is subtitled due to his Bristol accent (Don't know if it is true).
Regarding the original point though, I have heard some very loang, drawn out conversations to pass a simple instruction from ATC - and I am not always confident at the end that both parties have agreed on what is going to happen.
