It's definitely distracting, but any well-trained and disciplined performer learns to work through and ignore this kind of stuff. And, in my personal experience, it takes a lot to become distracted by something going on in the audience (because you're so focused on your performance and not on the audience).  The "no flash photography/no photography" rule is for the audience. Also, many performance venues also won't allow for recording/photography because they're paying someone to do that already. Not to mention that it's just in poor taste to do that regardless.  Fat people are the worst audience members. They talk loudly during performance, text/play with their phones (which is incredibly disrespectful to those around you and the performers, FYI), eat in the auditorium, get up to leave in the middle of a performance (you wait until intermission to leave, and only get up between sets/songs/etc if it's an absolute emergency).  In college, I volunteered as an usher for classical performances on campus. Most of the rude people I had to deal with were fat, and the only people I've ever kicked out were obese.