I cant answer that but I have been in the
building industry for over 30 years and
remodels and or demo will not use explosives unless the entire structure
is to come down. I did see another
video that suggested reflection from
an emergency vehicle. this makes more sense to me.

i have to admit when i first saw it i thought emergency vehicle but 1. the street's too far and nobody has ever seen this before. and 2. it's moving way too slowly and the reflected lights would change instead of appear exactly the same from the distance of this vantage. remember most of this video here is zoomed in.
Also i believe it is more of an action to bring the building down instead of remodel.
Curious and I just love hearing other theories.