Wedding proposals are a pretty special event for everyone involved, that pretty much goes without saying. There are a lot of nerves and everyone wants the whole thing to go smoothly.
The issue is, when you let Grandpa operate the phone to video the proposal things have a chance of going wrong. Not the actual proposal but capturing it on your phone so you can watch it and enjoy the special day over and over. Not all older people really understand how their phones work.
Take this guy for example. He had the camera on himself the whole time instead of using the front facing camera. At least they got his reaction to the whole thing on video?