I did this step according to this written guide, and honestly the result was not good, plus it is much harder to put the display back on when the 14 and 15 strip adhesive is attached onto the computer.
The video (also from ifixit) shows the correct way, putting strip 14 and 15 on the LCD itself. Have done it like this on a previous iMac I had and the results were much more pleasing.
