To Johnnik:
Yes, it would be interesting to know where and when this video was taken in Ukraine with active BUK radar. Actually Ukrainians must explain this. If there was a mistake, then such deployed systems would allow making mistakes.
But there are some problems with Ukrainian BUK's.
1. Why should Ukrainians shoot an aircraft that has flown through the whole Ukrainian territory and is about leaving Ukrainian airspace at flight level where Drones do not fly from direction that usually only friendly aircrafts come?
2. I doubt if Ukrainian Buks were physically able to shoot that aircraft down at that certain spot, deep in rebel territory. Buk wouldn't have that range for that height.
Instead of rebels whe removed their videos and postings, this particular video is still available.
https://www.youtube.com/watch?v=Q3MomxNHnUA