Quite interesting, I watched the video.
Hard to tell but what type of window is it, double or triple glazed or a single pane?
If double or triple I think it could be due to some kind of thermal expansion. I used to manufacture them a long time ago, mostly double glazed
Some are filled with gases like argon and the units are sealed using various materials, rubber, putty, etc. The actual facings are usually wood,
aluminium or PVC and larger panes tend to produce sounds when temperatures are changing rapidly or the inside temperature is significantly different
to the outside temperature, etc.
There are so many variables to say what it can or can't possibly be. Mostly, what you'll get from larger, thicker glass (maybe 6mm and upwards) and
especially toughened glass is loud, sharp craks and it's often down to the framework expanding or contracting. It can give you quite a fright if
you're not used to it. Smaller units with wooden framing can emit small sounds, I spent a long time working with this stuff.
Some glass also has metallic coatings like planitherm or pilkingtons own K glass, there's a lot to it so it's hard to say.
Still, it could be something paranormal who am I to say, just offering some opinions as it's something I worked with a bit in the past so not hoping
or trying to derail at all, interesting thread.
I'm really interested in the reply someone gave - saying it sounds similar to an experience a friend had in the past...something about not following
anything if you see it. I'd really like to know more about that if that's possible, maybe start a thread it sounds quite intriguing..
Flagged anyway as it was an enjopyable read.
To add - I thought it might be worth adding that double and triple glazed units are seperated by a spacer - this is usually a rectangular, hollow tube
with perforations which is used to speace or seperate the paned in the sealed unit. These spacers are filled usually with a thermal reactant like
desiccant to stop moisture accumulating inside the unit itself, which will result in eventual breakdoan of the seal and seperation of the sheets. This
too can react to temperatures and cause some sounds to be heard, sounds can range from small, creaking or cracking sounds with small units to loud,
sharp and quite startling cracks for large, thicker units.
edit on 10-7-2015 by samerulesapply because: Additional