There is no good guide about this one, all i know is:
-Only the TVs with a message count.
-We only need to read the first message of the show to make it count.
-The first TV that counts its on the lvl 3.
-1 at the very start of chapter 4
-1 in chapter 5 near a key
-1 in chapter 6 right after the 1st enemy cop
-1 in chapter 6 after watching the cameras, the screen does not show any texts, just laughts
-1 in chapter 7 when you face the 3 cops in a room with a key ( pretty sure its 7-1)
-1 in chapter 7-3 near the key
-1 in chapter 8 right at the start
-1 in chapter 8-2 after you disable the police alarm, its right next to the alarm
-1 in chapter 12-2 right after you kick the 1st door

Help me telling me which levels got the TVs with messages so i add them to the guide with screenshots to update it.
I got 8/9 of progress and i have no clue about the one i am missing, its the last achievement i need to get.
I received help from: Dbkibas and 010110100110010101100100