First, the detonation velocity they cite (something like 4500-6500 m/s) is nothing exceptional in the world of explosives.

 

Second I suspect this is a very unstable explosive that isn't particularly useful in most cases because there is way too much chance of it blowing up at the wrong time. First of all, most high explosives require a significant *burst* of energy to initiate the explosion--usually requiring an explosion to do that work. The fact that that only the heat of a burning fuze is required to initiate this explosion suggests that similar sources of energy would also detonate it.

 

I suspect in fact that the reason they wrapped the explosive in tape is that just the friction of sliding it into the pen might have been enough to detonate it. I noted the mixer trying to stand the matchstick up and then choosing to set it down. I'm suspecting this was a safety measure becase the fall of the match stick might have been enough to set it off. This is nothing unique. There are plenty of unstable explosives. They aren't used for anything except blasting caps though, because any other use is too dangerous. In fact, that basically what they made in the video.