There's a big difference between waving at a coworker's kid for a second during a video conference (why would this make you uncomfortable?) and someone actually bringing a child to the workplace (which OP didn't do, and would actually be disruptive).
Yep, if it just stays at that it's fine. I find with the types that are likely to turn on their webcam for their kid, there's often more that follows as interested colleagues egg on conversation. That's fine, it doesn't bother me until there's an expectation that I participate in this conversation, which unfortunately doesn't seem to be as controllable (kid sees me on video or my screenshare or whatever and starts asking questions).
No, it's not that big of a deal, it's just something I'm not interested in interacting with, and if you're the guy who always has to introduce his kids at the beginning of conference calls, I'm probably going to generally avoid you unless I absolutely need you for something.
I'm sure if I had a kid I'd feel entirely different, but I don't. I also try not to involve my lifestyle choices on conference calls, so I really feel this doesn't go both ways.
