I don't find it "annoying" per se, but I truly don't understand the idea of videotaping (I said taping...I'm so old...) fireworks or the other shows, especially if it's the first time you've seen it. I would so much rather watch the show through my own two eyes than through a video screen...when the event is happening right in front of me. Sometimes I'll see people hold their phone/camera up through the entire show. I'm not watching them, I'm watching the show, but I do notice it. I can't help but thinking they're missing the show. I suppose if you've seen the show many times and you want to video it for someone else, I get it. But if you're a first timer, put the phone/video down and enjoy the show with your own eyes. As others said, there are plenty of videos on
YouTube of most everything at WDW. And yes, I agree, if you're going to pull your video camera out, be courteous to others around you.
Years ago, when my kids were younger, I did put them on my shoulders. OK, well, one at a time. I'm strong, but not THAT strong.

Before I did, I looked around to make sure there was nobody directly behind me. And yeah, that's a tough problem to solve, because I really do understand both sides of that issue.
Only other thing I can think of that bothers me is when I see people doing things they're really not supposed to on the rides. Standing up, touching things, etc... They're likely the same people that cause the ride to be shut down and restarted (I've been told by CMs that 90% of rides going down are due to guests doing things they shouldn't).