It's crazy because I definitely watch movies while doing calisthenics. It's not like I really need to pay much attention to anything other than counting and it makes the time go by more quickly. And I listen to music when I run for the same reason.  I'm not missing out on anything. People watch themselves when they lift to monitor their form but they can also listen to music and audiobooks. I guess since they've never given exercise a chance they wouldn't know this.