Start with digital picture frames and work your way up.
Not even sure it can be called hacking, he used the credentials that was apparently showed at the billboard at one point...
> Reports suggest the man hacked into the system after seeing log-in details displayed on the billboard.
Start by not planning to do it in a Muslim country.
If you hacked a billboard in the US and displayed a porn movie, you would be in some serious shit. Not only is hacking a federal crime, the RIAA and their ilk would also do their best to nail your ass to the wall (no pun intended) for broadcasting without permission.
But nobody can put you in jail just for having porn