He isnt changing the color of the NVG, hes using a message:
Code:
message_begin(MSG_ONE, SVC_TEMPENTITY, {0, 0, 0}, id)
write_byte(27) // TE_DLIGHT
write_coord(origin[0]) // X coord
write_coord(origin[1]) // Y coord
write_coord(origin[2]) // Z coord
write_coord(radius) // radius
write_byte(250) // red
write_byte(0) // green
write_byte(0) // blue
write_byte(250) // brightness
write_byte(10) // life
write_coord(0) // decay rate
message_end()
TE_DLIGHT stands for Temporary Entity Dynamic Light
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