That's One Less Mi-17...

Well, that certainly went poorly for the Syrian Air Force such as it is.

Slowing the video you can see the extremely long tail boom that is indicative of the Mi-17 used by the Syrians.  Traditionally a transport helicopter some countries have turned it into a gunship of one kind or another.  In production since the 70's in Russian factor its not modern or advanced but it is likely cheap and a great addition to any would be, third world, dictator's arsenal.

According to various sources, Syria has, er....had...some 90-100 of these in both transport and gunship versions.  Can't tell which version this is but given it was hanging around a contested area it would logically be a gunship version.  Then you look at the height at which it was hit and it appears the rebels have more than just small arms fire on their side.  Smoking on its way down it appears to have sustained substantial damage but its the catastrophic explosion that is the showstopper.  There is literally nothing left afterwards and little debris comes raining down.

I'd look at common, portable, surface to air missiles fielded by Turkey and Qatar (the two major backers currently of the Syrian opposition) if I wanted to know what it was that brought this hulk down.  Congrats to the hunters.

10/18/12--Edit to add: Oh, hey looky...a front page story from the WSJ today on how Syrian rebels are getting shoulder fired surface to air missles from Turkey amongst others....ahead of the curve...ahead of the curve....http://online.wsj.com/article/SB10000872396390443684104578062842929673074.html?mod=ITP_pageone_0