Genius comments: The Briefings are located in three “Fight for the Light” alerts.
Near the back right hand side.
Star Labs (4 Total):
[Credit to Gardian66 from DCUOPC forums]
-In the lobby, just above on the platform, you have to look to the direction of the starting point.
-(Fear Side) Near the 6th of the 7 things you deactivate.
-(Fear Side) Behind the big boss room. Do not go in, go around (left side I think) Should be ground level.
-(Will Side) Secret Room where you pass through the left door with debris of the first big room on Will side.
Note: you have to look for Star Lab Briefs as you go thru the alert. Once you complete the alert you are locked out of some areas
Coast City (4 Total):
[Credit to MisfitPrince from Gamefaqs forums]
-behind the starting point (i think)
-inside the ruined building (where you battle crazed green