"What matters is not whether you make mistakes or not"

It's certainly true that we all make mistakes, and it's important to learn from them when they happen. But it's also true that sometimes it does matter when you make a mistake, and learning from the mistake won't necessarily erase the consequences that the mistake produced.

So it's not a bad idea to at least try to avoid making the more obvious mistakes in the first instance, and I'd think that operating a video camera while belaying might fall in that category, at least under normal circumstances.