in a sane political climate, this would be a curiosity[ - something weird that nobody really cares about. but, bernie has painted himself into a corner by playing up the russiagate narrative so dramatically; had he been less fantastical on this narrative, which most good observers saw through, then he'd have a more rational footing to react to this from.
i don't know how many democrats there are out there that are going to get conspiracy-eyed over this. i'd guess that, right now, there are probably a measurable number of them. he may have talked himself into a lot of trouble.
the in and out candidate might be him.
https://www.politico.com/story/2019/05/17/bernie-sanders-mystery-soviet-video-revealed-1330347