It's a bit of an undertaking to watch through ... well, not really, but for those with limited attention spans, at least check out minutes 8, 15, and 17.
Affordances are relational, a connection between you and the object you are interacting with - the more you see of them, the more ways you have to interact with it.
In the case of single combat with blades, there is a purpose to the interaction - prevailing against your opponent - so the affordances in this case relate to achieving that end. And the object that you are interacting with is your opponent ... and the weapon they are wielding.
There are many different ways of reaching the goal (i.e. stopping the opponent), a little like paths through the forest. Each has a start point that connects to the next, and so to the goal.
The more paths you see and the more affordances you can grasp, the more ways there are through the forest.
Each path demands certain skills, many overlap, yet each path is slightly different, and along that path, the possible branches depend on your ability to see them.
One path may be - Cut weapon hand, opponent drops weapon, finish.
Another - Threaten opponent's head, bridge created through weapon contact, close, shunt opponent away, cut to finish as they fall back.
Perhaps another - Feign an opening to cause the opponent to rush in, step off line, drop weapon and cut under opponent's strike whilst stepping past and away.
So many ways, so many potential solutions .... and so many moments where the situation can change.
If each moment contains an affordance, each part needs practice both to see it, and to be able to do something useful with it, whether it succeeds or not.
For instance, hand targeting requires accuracy and speed, and the follow up requires the ability to recycle efficiently, bringing the weapon up on target as fast as possible. It also requires a knowledge of range and evasion.
However, should circumstances shift during the hand strike, one might fail to hit the hand, and perhaps connect with the weapon instead. This gives a bridge, and thus the possibility of the shunt back and cut ..... Or if the opponent retracts the hand, now perhaps one can close using only the live hand to control the opponents weapon, and you can just cut on the run by ....
Start from another place and more affordances occur, but appear and connect to each other in different ways. Each part needs skills, and the ability to change paths in mid stride if something does not go as planned.
If the path begins by drawing the opponent to block and creating a bridge, it require the ability to express a strike, in other words to make it look as threatening as possible to elicit a reaction. It also requires good weight shift and footwork to drop into the bridge directly behind the block, and the follow up requires a knowledge of anatomy and structurally strong and weak lines, and the ability to cut a falling target.
If the block you need your opponent to do does not manifest, what of this moment? Can you just follow through with the strike and hit them? Do they back up? Perhaps this affords the opportunity to close anyway? And if they strike at you ... and you block ... is that not the same position that you were looking for originally ... as long as you can gain the initiative?
Feigning an opening requires acting ability, though just missing by accident works well too .... but both require evasion which requires footwork and a knowledge of cut angles, where is dangerous, where is not, and an appreciation for the importance of the exit.
All require a knowledge of range and timing, how a sword works (and all the affordances it gives), how people move, and most importantly, how to not get hit yourself as you pull off the win.
One of the great things about flow training is that you can work on each, separate, piece within the flow - hand tagging, evasion, bridging, whatever, OR you can chain the whole series together to the end game.
The ability to break down the whole into bite sized pieces means that more paths through the forest can be uncovered, and the more often the affordances, or 'nodes of opportunity' if you like, will 'appear' to ultimately join up into a map, all leading to the same destination.
Anderson Silva is a great fighter, and I appreciate his movement from a sword perspective as he plays more like a sword player than most MMA guys do (Lyoto Machida is perhaps an exception).
His use of 'physical psychology' is great, tiring his opponents out, making them make mistakes, or avoid certain games, both through creating fear (of pain) and anger (at his antics).
Of course, playing the margins comes with it's dangers - feinting and especially baiting work because the opponent believes either in the threat, or that hitting the target you are presenting them with is possible.
Obviously this also means that you are essentially in range, but using your weight shift or angle to evade at the last minute. Get too cocky and things can go horribly wrong.
Here is an awesome piece about Anderson Silva's recent miscalculation by Tim Marchman.
(I like how Tim Marchman writes - he makes me laugh. Here is another piece, this time about Chael Sonnen, which is great AND shows a great gif of Anderson Silva and his tactical prowess - causing the mistake, nice evasion, taking advantage)
There are many errors I see in peoples' movement during flow -
1) They do not move at all - Sitting target
2) They move in a predictable rhythm - Predictable target
3) They only move in response to the opponent - Behind the timing
4) They move as though the opponent is not there - Dancing their own dance/Easy to hit
Not moving is only be a good idea if you can catch your opponent off their guard RIGHT at the beginning of an encounter, before they are ready .. or then momentarily within a movement flow. After that, movement gives you SO many advantages to exploit over standing still, and keeps you SO much safer, that it's a no-brainer to keep moving. Thing is, there is a way to move that makes sense, and many many ways to move that do not. Everything you do has to have something to do with what your opponent is doing, yet in cannot be as a reaction to what they are doing. It has to be unpredictable to them, yet connected to their movement. It has to make tactical sense, keep you safe, worsen their position, and limit their options whilst keeping yours as open as possible.
It's like dancing ..... yet with a somewhat different goal ... the demise of your dance partner.
It's a skill. It's important, and though it may become intuitive, it takes practice.