Well, like in many historical fencing styles they set up different guards as templates of a sort. I hope VorNach will chime in on this as this is not my main area.
What you're referring to may well be in line with the video... based on what I saw of VorNach's guards in his latest Djem So video, I think we're talking about the same thing. I'll be interested to see if he has any input here, as I don't have as much experience in the classical fencing styles.
You rang?
I will elaborate a bit on the parries themselves though.
Each zone has a corresponding parry designed to close that particular area of target off. For instance, an attack to the head is thwarted with a parry 5 (taken from saber). This is what I take as the "guard" concept, the closing of a section of target as opposed to the deflection of an attack in progress. I suppose in this way it would help to differentiate - perhaps call the former a "guard" while the latter could be called a "parry." The guard would be more useful against cutting attacks, but is rigid and therefore takes the full force of the attack. A parry, being executed by deflecting an attack away, would be more suitable for thrusts... but would hold the advantage of not meeting the attack head on.
I would like to expand on the ideas you are presenting Master Nero by adding some elaboration. Maybe I’m just making it more complex but I’d like to unpack the ideas a bit more. The major distinction is the guards are positions offering a sort of passive defense while parrying and blocking are actions you take when contending with an opponent. Attacks, parries and blocks will all start, finish and / or pass through one or more guard positions in the course of the encounter. They form a sort of framework to attach the various techniques of the style to.
Since I’m using some terminology a little differently than how it has been presented so far I’m going to define the nomenclature, based on my background and experience, as I go along. These may not line up with everyone else’s definitions; this is just so there are no misunderstandings in what I am referring to.
“Guard” refers to a transitory body (and weapon) position, used to protect a specific area. As Master Nero said this has the effect of closing off a target zone. Because this area is mostly blocked off it leaves open other areas, inviting the opponent to attack somewhere that you are, hopefully, using as a way to open them up for your own attack.
The protection a guard offers comes from simply being in that position. As with Master Nero’s “parry 5” example simply by holding that position downward strikes to the head and shoulders are unlikely to work, thus an opponent is unlikely to try such an attack while you are in that position.
Guard positions thus change as the relative positions between the combatants change; each person may change the distance and guard position to entice the other to either take an action or change their own guard, perhaps opening up too much in the transition. This could be an entire conversation on its own.
Guard positions also change as a result of launching attacks. Attacks are normally launched from, sometimes pass through and finish in guard positions, unless (and sometimes when) your weapon is embedded in your opponent.
An example of this is in Master Nero’s video at about 01:06. He moves from a high side cut up into position 5 from which he launches his own downward cut to his opponents head.
“Parry” is an action that prevents an incoming attack from landing, preferably without dead stopping the full force of the blow. A parry will typically pass through or finish in a guard position in the process of being performed.
Going back to the diagram below if you are in Guard position 4 and your opponent lunges or cuts to your right shoulder/pectoral area you bring your blade across towards Guard 3. As you come into that position you intersect the incoming blade, deflecting it past you or perhaps beating it out of line.
“Block” is an action that stops an incoming attack by interposing something between you and the attack; this typically results in stopping it by absorbing the full force of the hit. A block sometimes ends in one of the guard positions.
The most straightforward example is going back to the 5 position. A downward cut to your head is intercepted by raising your blade above your head, stopping the blow. Not necessarily elegant but if it’s that or the worst (and last) headache of your life do what you need to survive.
“Empty parry” is a defensive move (it could also be an “empty block”) that only defends; it does not threaten the opponent. These sometimes end in Guard positions.

…in some cases it is more beneficial for the Makashi stylist to deflect strikes in order to prevent being overwhelmed. In fact, this approach can be useful in unbalancing a more "wild" opponent, especially a less experienced one.
Absolutely. I would further offer that it’s always beneficial to deflect an attack rather than block it, when possible. This is a step towards the idea of making all of your deflections a simultaneous attack. When you stop your opponents attack without threatening them in some fashion at the same time (the empty parry) you have given them another, free opportunity to attack you. If your defense also is an offensive or threatening technique you put yourself in a stronger position in the encounter.
The classic example of this from foil fencing occurs when an opponent lunges at the left side of your chest. You parry into 4, extending out at the same time so while you are deflecting your opponent’s blade out of line to your left, your own point is extending towards them. In effect the riposte is part of the defense.
The German longsword version of this is a downward cut starting from the high guard, traveling into the longpoint guard and hopefully at that point your opponents head. While it is targeting the opponents head your blade is between your upper target areas and the opponent’s blade. You’ll see this in most of the longsword videos that have been posted in various threads.
Alright, now that my novel here is done I’ll stop. I hope this answers the questions people had. Hopefully it generates some new ones as well.