By the looks of those logs, looks like they might be prototyping some kind of underwater pellet mill.....
After further review, I think this is a fake. I came across an article that said a video like this was taken from a Finnish underwater demolition company's website and was it was posted as a lightning strike but was actually demolition charges. The article didn't show the video but had a picture that appears to be this river.
If you look in the upper left you can see the charge as they are clearing silt from the river. this was caught by my eagle-eyed camera operator cousin.
The vapor color gives it away....shooting tannerite you get the same colors.... I've also seen it strike lakes with no visual disturbance.
That's what got me looking to see if it was a fake. I watched a couple of other videos and like you said, no disturbance to the lake at all.
Too bad it wasnt lightning. i started making my lightning gun for nothing. i would have had endless years of fun with that.