Missed this the first time around
...i did think it was a bit strange that you went past that
History is not abstract. To be abstract is to be theoretical or lacking in concrete existence. History is anything but, rather it is the record of events that actually occurred. Various wars happened, the weapons and techniques used in said wars happened. They are facts not abstract theories.
This is 1/2 true. In history, we lose out on details. But, i'll talk more about that in a second.
All a CCTV camera does is provide another way of recording and storing past events, aka a new modern method of recording History.
It's more than that - It's irrefutable and verifiable evidence. History is a description of what may have happened. We know that Filipinos fought of Spaniards, but the details are only as good as the person who wrote them down. On video, we see everything, and draw our own conclusions. I can provide you with visual information which you can interpret as we see fit - With history, i can just point at drug dealers getting shot, and we can daydream about how long their killers spent at the shooting range.
The reason for the lack of CCTV footage is simply this.
Wait... what? There's HUNDREDS if not THOUSANDS of CCTV videos readily available. There are videos of people fighting off committed knife attacks, and most of them are untrained, elderly, and unarmed. I didn't even want to go there - I was just bringing us back on point...
1. the number of people who study martial arts is small. In the US, as an example, it's roughly 5% of the population (current population is over 318 million the article sites a study noting 18.1 million study Martial arts)
2. the number of martial arts that focus on techniques that make for potentially effective knife defense is even smaller than that
3. the number of instructors that focus on said techniques is even smaller.
4. it takes a fair amount of training to be able to pull off the techniques, if taught, and the ability to not allow your fear of the knife make you "lock up"
...i'm not going to go there. This is a can of worms i'm far too inexperienced a debater to have a go at.
5. the penetration of CCTV cameras is far from universal, I think the UK has the highest penetration
6. CCTV footage that does exist often doesn't make it to YouTube due to privacy concerns.
Google Video Search.
So we have footage of people using MAs when attacked but of all the footage of people being attacked what % is that really? Then you add in the factors above regarding training and really the chances of such a video being captured are pretty slim to practically nil.
Who cares? If we're going to research knife attacks, filtering it down to trained MA'ists successfully using the things they've trained at so that all of their time and experience pay off is some of the worst sampling bias i've ever heard of. We look at the problem and we see if and when and how our theoretical solutions fit into it.
So you then look to History documented by other means.
If history is telling a different story to irrefutable and verifiable evidence, we have a problem.