It's not gloss. It's raw LCD.
Kensington locks are nothing more than a joke. Opened in seconds with just about anything, been common knowledge for years http://www.youtube.com/watch?v=IIQIJpOhV4c
I am fully aware it's a Raw LCD (uses two pieces of bonded glass but not cover glass to protect the LCD) - it still has a gloss finish and reflects its surroundings.
My Kensington lock is not as useless as the one shown in the video and cannot be disabled with a plastic tube - my combination lock could be cracked (more seconds to achieve and be caught in the act), forced or cable cut with croppers.
I stated 'opportunist', your video link for the lock in question is not common knowledge to 'everyone'. Often people will steal on the spur of the moment without going equipped for stealing - too much temptation presented to them through insecure items which can be lifted in a split second. Thieves obviously do not want to be identified and are unlikely to hang around the scene of their crime. The majority of house burglaries take only around 2 minutes which includes the time taken to force entry.
In past years thefts from press centres have involved gear laying around for the take - cameras, lenses, laptops and even colour negatives (USPGA 1998).
All of the professional sports photographers that I work alongside, lock their laptops - some insurance companies in the UK will reduce claims if the laptop is not locked at sporting venues when the photographer is absent from the press centre.