I'm pretty sure that the hint command is only executed client side... so if you have a trigger that uses the
player command, it will only go off for that player.
Similarily, if you're running a script only on one machine and you use a hint, only that machine will display the hint
You can launch a cutscene for only one player (or group of players), but it can get pretty complicated. It involves ensuring the cutscene script is only run on certain computers...
However sidechat will be displayed for all computers.