That snippet was written by Spunky as an example and comes from
this thread.
But, in the futur, if you have additional questions regarding this script then please post in the original thread instead of creating a new one.
--------
Some very important note on those registry keys:
HKLM\\SYSTEM\\CurrentControlSet\\Control\\Class\\{6BDD1FC6-810F-11D0-BEC7-08002BE2092F}\\
0000\\Settings\\LVUVC_LEDControl
The drivers aren't located in every system in the same configuration set or in the same order. So the
0000 might work for your personal computer and system, but not for others. Also there are probably more drivers installed, and they might not even be from Logitech. This means that there might be more than one configuration set (eg: 0000, 0001, 0002, 0003, etc).
--
To answer your question:
Not all Logitech webcams have those leds and even less webcams support toggling the led on/off. So simply testing if there is a Logitech webcam wouldn't always work, in fact it would rarely work..
The best solution is to test on the existance of those very same registry keys already used in that script. That is: a subset of it like the
MatchingDeviceId,
ProviderName and
DriverVersion values. And this for all the LED-toggle supporting webcams from Logitech.
Also see
here and
here.
If they exista dn have the correct values, the user probably has a Logitech webcam which supports toggling those leds on/off.
If they don't exist the user either hasn't a Logitech webcam, or his/her webcam doesn't support it and your script shouldn't be trying to set those keys...
Actually you should always check for the existance of keys before you change them anyways. Otherwise if somebody (without such a webcam in this case) runs this script his/her registry will be polluted with useless registry keys!!
--
And last: by simply setting those registry keys you can not enable/disable the led on the fly. You also need to reinitiate the camera each time (eg: by plugging it out and back in).
--
Remember that this script is not a complete script, but simply a quick but in most cases working example.
It does need some fine tuning, like the stuff said in this post, to make it work and to be 'safe' to use for the general public.
/ 
