REminder, keep video checked off in preferences in any sim that has a land owner you do not trust.
This is because llSetParcelMediaCommandList is not restricted to the parcel that it sits on, but can alter any av anywhere in the same sim.
This gets me back to one of my pet peeves: 16M parcels. There is no reason for them except land griefing, they are a security problem. LL should institute something rather simple on mainland: minimum parcel sizes. That way if people want to put up with the visual noise and security risk of 16M parcels, they can, and buy land for less because it will have a lower value.
LL claims this is not their fault, this is not true. Apple's Quicktime has a bug, but LL's video streaming system is Broken by Design and their land system is Intentionally a security risk. And they make money from this.