Complex sentence: Later, on different occasions, videos showing rebels using the system appeared, until, on 16 January 2014 a video of the shoot down of a Syrian Mi-8 or Mi-17 helicopter was uploaded.
Split into simpler sentences: Later, on different occasions, videos showing rebels using the system appeared. On 16 January 2014 a video of the shoot down of a Syrian Mi-8 or Mi-17 helicopter was uploaded.