The cable transferring the actual data to the LCD got more width - about the same size as the battery connector - and its socket is near the right fan ( when the laptop is sitting infront of you like normal work ).
look here & here.

Please please please make yourself a favor - and WATCH THESE LINKED TEARDOWN MOVIE, inorder to understand what is what - SO YOU MIGHT AVOID SCREWING-UP your G751.

back to your image...
that looks like a wifi antenna connector - and it sits around the LCD in the monitor unit.
worst case scenario - when you connect that cable back to the wifi module and boot up OS, you won't have good reception.

you can always DIY - buy such cable inc connector, or just soldier an extention to the small wire+connector you've already ripped off the screen.
note that wifi antenna best sit in the monitor due to various shielding design asus made in advance - but you can always make trial & error if you don't want to open up the monitor part to insert the wifi antenna. ( you can drill a hole in the shell to have a tail out of the laptop - again - worst case ).