The clear casing on the 33 headlights do come off... its a huge hassle though, from memory you have to unscrew both and take them off the car completely, then use a heat gun (carefully!!) to soften the plastic between the black casing and the clear plastic so that you can seperate the two.. you have a chance of breaking or ruining them if they are not done properllllly. but if it is the moisture on the inside its probably worth it.
As Chris said above 'Meguiars Plastx' is awesome stuff, got my headlights clear as, and got that yellow tinge outta them. About $25ish but worth it for sure, may have to order it in like i did though.