Why would adding a dash camera interfere with you warranty? Unless you mess something else installing it. They typically get power from the 12 volt outlet, so you don’t have to cut any wires. Plug and play.
Why? Stupidity. If a dash cam or any add on accessory/item is properly installed there is no reason for its installation to effect the warranty. But we are talking about humans here.
We all understand that a + sign next to or on a battery post is the positive post and a - sign next to or on a batter post is the negative post. Apparently this guy never got the message.
Either that or, this guy didn't understand that when his buddy told him that to get cold air in the summer you needed to reverse the battery connection, was a joke. Either way no auto manufacturer is going to cover this under warranty.
The other situation that I can think of is if the item/accessory critically malfunctions causing damage. If the copper top batteries (not picking on Duracell just an example) leak inside your radio, Motorola isn't going to cover the damage done by the batteries.
I'm not saying that a dash cam will critically malfunction, I have never heard of one critically malfunctioning, but I won't say it can't happen. Knowing that I am still looking at a good dash cam system to install in my Passport. I have the knowledge to install one properly and safely and am willing to take the risk that the thing will not critically fail as history is on my side.