At the start of the video we see the bomblets being plucked from the ground, itself extremely dangerous, and the fuze being removed. We then see the rocket workshop with rows of these bomblets on the ground, all with the fuzes removed, and we're then shown a bomblet having it's tail fins removed, and replaced with a fitting that then allows it to be screwed into the rocket. A newly manufactured fuze is screwed into the bomlet/warhead, completing the rocket.
What this video shows isn't just simply the bomblets being used as warheads, but that there's an entire manufacturing process behind this, with new fuzes being made, the new fitting being designed and manufactured specifically for this task, and the rockets being designed around carrying the bomblets as a warhead. It really shows how sophisticated the manufacturing process for making these DIY weapons has become.
Thanks to @HamaEcho for the video.
Unexploded Bombs Used In A Truck Bomb By Jabhat al-Nusra
Clear Evidence Of DIY Barrel Bombs Being Used By The Syrian Air Force
Cluster Bomb Usage Rises Significantly Across Syria
Collected ODAB Thermobaric Bomb Evidence
A Beginner's Guide To Identifying UXO In Syria
The Mystery Of The Syrian Barrel Bombs
You can contact the author on Twitter @brown_moses or by email at firstname.lastname@example.org