It was hilarious. I previously hadn't laughed so hard in my life.
But, apparently, comedians getting attacked by flies is commonplace? Here is Eddie Izzard with his own kamikaze insect. How do they train these creatures? What's the cue? There was definitely a fly which came to savage Bill, and you can clearly see a fly here too. Do they lure these flies with their discarded shitty jokes, do you think? Perhaps the rotten fruit that was once thrown at them when they were just starting out and not particularly good? Enquiring minds want to know.