Operating TV while driving down the road.

In at least 39 states it is illegal to view a TV while driving.

source

list of states

Typically if you have an inverter this is a switch somewhere to turn it on. Also, if the TV is mounted in the dash or in the cabinets over the windshield there is likely a device installed by law that will not let the TV operate when the ignition is on.

There should be a switch and not all outlets are usually powered by it.
And most RVs have a relay that prevents the tv from being on when the engine is running. I have defeated that on all my RVs either by disconnecting the relay or the wire or using another outlet. Ain't nobody's bizness but mine if the TV is on going down the road.

I hope the tv dvd is in the back seat and you aren't watch it while driving.