"This is a video of the barrel being tossed out the back of the helicopter. As you can see, it takes several long moments for it to reach the ground. This is why this weapon of choice from Assad is the most dreaded by people in Syria. The length of time it takes to fall is too short to run since the blast radius is so huge, yet it is more than enough time to contemplate your impending death."
Matthew Aslett was pointing out that another reason for loading TNT into dumpsters and chucking them out of helicopters is that it is cheaper than proper bombs. That is useful for a state that is running out of money.