Hijacking Individual Screens
No need to futz with the fragile TV system.

While I've been told that hijackingg a TV channel with arbitrary recordings could apparently really break how TV shows and whatnot are stored, I have had another, sort of similar idea, this time for individual televisions/screens

I think deckers should be able to display a short, custom "broadcast" (using this term loosely) on specific screens that they have access to. For example:

#device-execute-command
1234
broadcast_hijack
[Stock footage of a WW2 dogfight plays, while a voice declares:] MESS WITH THE BEST, DIE LIKE THE REST!
#enddevice-execute-command

Which would show up as:
The television/wall screen/whatever flickers, the current broadcast cutting out.
On the television/wall screen/ whatever you see: [Stock footage of a WW2 dogfight plays, while a voice declares:] MESS WITH THE BEST, DIE LIKE THE REST!
The television/wall screen/whatever flickers again, returning to your scheduled programming.

As this works based on individual displays, rather than the main TV scheduling system, I feel like this would be a lot easier to pull off. As for the maximum length of the hijack 'message', I don't really know, but it should be long enough to have fun with without being too insane. Like, we don't want people putting whole novellas in there.

Of course, it could be easily thwarted by just… turning the TV off. Maybe also a command to remotely turn the display on? I know there's already device commands for enabling/disabling transmission on the device, but I think that's separate from its actual power state.