well they were delaminating....you know that peeling thing that comes on it ? well...one of my headlights, im pretty sure you can guess, was worse than the other. basically u sand it off then polish it.
i think the polish acts as that....but basically i didnt really follow that diy..i just got the sand paper (1200) with a bucket of water with a cloth in it. i put the sandpaper in the buck, wet the headlight started sanding. and when the sandpaper got stuck on the lights cos it was getting dry, i just wet it. then i used some polish i got from petrol station (not the same brand as the one in the diy but worked fine ) and rubbed it in with the cloth.
The whole idea of sanding then polishing is to remove the laminate all together so all you are left with is the plastic. Problem is, the plastic oxides & becomes dull again because it doesnt have the protection of the laminate. They key is to sand & polish, then relaminate. There are special sheets of laminate you can buy apparently. I've not dont much homework on this but some folks have... hopefully they'll be along soon to add something.