According to the Facebook page of Saif al-Islam brigade the aircraft was shot down during a raid on the "Al-Anadan checkpoint". The video is pretty unclear, and it's not certain if the video is genuine or not, but I will be keeping an eye out for more evidence as the day goes on.
The Free Syrian Army Captures SA-6 Surface To Air Missiles
The Free Syrian Army Storms A Surface To Air Missile Facility
Helicopter Downed In Damascus - Collected Videos And Images
More Evidence Of Complete SA-7 Anti-aircraft Missile Systems in Syria
You can contact the author on Twitter @brown_moses or by email at email@example.com