slats, for me timeline look like that:
1) Info about plane lost
2) Info that crash site was found
3) First photos in the press and at the forums
4) ISIS claim (just banner with some Arabic posted)
5) More photos and info that plane was destroyed at altitude and that there definitely was fire ant that tail separates
6) Video posted with comments "plane was shut down by us", quite quickly removed
7) Agreement that there was no traces of any missile
7) Video posted again with "we did it but we will not tell you how"
Am I wrong?
I'm not sure there was any claim the plane was shot down. I think this was an assumption that got incorporated into media reports. I may be wrong however.
Also, it would not be surprising if ISIS had a generic banner prepared in advance, and followed with the actual recording a short period later.
So I'm not sure the above sequence of events makes it less likely to be genuine.
We may just have to wait and see - time will likely tell if it is genuine or not.
If this video is true, what will Joe Public think? I believe he will think "These guys can bomb a plane with such reliability they can pre-position someone to record it." That is a pretty frightening thought.
As such, if it is true then don't expect our leaders to confirm its legitimacy.
Conversely I believe our leaders would have been quick to denounce it as a fake if they could. We would have been referred to the real incident. Or we would have graphics experts telling us it was computer generated and why.
In this case, the silence is deafening and (to me) suggests it is accepted as genuine.