I seem to recall another episode of QI when it was said that wearing black or white made no difference in retaining/reflecting heat. AH, just thought; light is absorbed by black, but not heat. Er, sorry, I'm waffling now.

Working with lasers, id hazzard a guess that it is the specific wavelength of the laser that does not interract with the absorbtion of its energy when presented on a white interface. Im sure any non-white color would just as easily have caused it to burst.

I remember that it was about the clothing of nomadic Arab tribes I think..

I wonder if a green balloon would pop from a green laser.

I used to yell at the TV when this infomerical came on. If I remember correctly, they screwed up the paint on a black car with the same laser:
http://www.youtube.com/watch?v=AIDei7clylY

Don't know the episode you're referring to but heat = infrared light and absorbed visible light, if I remember correctly, becomes heat, at least in certain circumstances.

The balloon is basically vulcanised rubber, or more commonly known as latex. The lasers I work with have certain interractions with the water content in silicon fibres. Different wavelengths (colours) react differently within different fibres.

1550nm for example sits just on the absorbtion point of water in silicon, so it loses quite a lot of its energy along a fibre due to that water absorbtion in non-pure fibres. 1310nm lasers however dont have this issue, and can hold their signal for far greater distances.

Different coloured lasers, interacting differently with the exact same material.

One has its energy absorbed, one doesnt.

.....im guessing a similar principle occurs here.

(Im in telecoms if you hadnt guessed )