How is this OLED cable being soldered to PCB?
Some solder is already there, on the PCB - so he only need to melt it. He covered board with thin layer of solder in the very beginning. 
It's flat flex cable or "Flexible flat cable". 


Regarding soldering in another way - if it has connections on both sides, they are electrically connected and you reroute the PCB to match mirrored pinout - you are likely good to go.