I saw the same thing while watching the video. It was not a demo charge, i've never seen C4, or any other demo charge/cord/explosive, flash blue like that. What first caught my eye was the street light getting much brighter briefly, that told me instantly this involved a high level of electricity.

Edit: Another anon pointed something out that does make a lot of sense. If you watch the street light closely, right before and during the flash, you can almost make out a person under the street lamp. It does also look like backflash from a possible rocket propelled weapon. The explosion pattern does align with this as well as the debris exited to the opposite side. So...someone blew it up with a weapon. It wasn't a charge explosive or lightening strike as I originally thought.

I saw the same thing while watching the video. It was not a demo charge, i've never seen C4, or any other demo charge/cord/explosive, flash blue like that. What first caught my eye was the street light getting much brighter briefly, that told me instantly this involved a high level of electricity.