There’s no other word I can come up with to describe what I just watched.
An absolute fraud, and I’ll show you what I’m talking about.
If you watch the one-handed swing, this dude is pulling the club way outside-in and hard across the line to the left.
If you even make contact with the ball with this type of motion, you will be slicing the heck out of it or pulling it across five fairways – or perhaps pull-slicing it. Or pull-hooking it.
What any of this has to do with creating lag, you’ve got me:
Here’s what it looks like:
Outside-In Club Path
That is a club path of death, and you can see that on this “drill,” he is wide open with the shoulders at the swing bottom, which is the only way to swing this way.
Compare that with what I have shown the club path looks like swinging with the leading arm only:
Inside-Out Club Path
And what the tee does with an inside-out club path when I hit it:
Seems like that tee went pretty much down the line, yeah?
OK, now watch this dude’s shoulders at impact with his actual swing, and compare it to his practice one-handed swing:
So, pretty closed just before impact, slightly open after impact, and the missing frame would have shown you nearly perfectly square shoulders to his target line at the actual moment of impact.
In other words, an inside-out club path into impact.
But he’s giving you this to do:
And the difference not only in club path, but the shoulders and head positions:
If you wonder why you can’t make a decent swing after watching YouTube “pros” giving tips, I can offer you a good guess.
If this isn’t fraud, it sure smells like it. Either that, or a guy teaching golf on the internet who has no clue what the body actually does in the swing but pretends that he does.
Either way, I’d call it fraud.
WAX Golf 
the reason MCS flies straight is because the proper shoulder closure after impact is an out-to-in motion, so we’re hitting pretty much 0° at impact?
so in-to-out right before impact and out-to-in right after impact – basically moe norman’s in-to-in tangent point contact?
also guessing you get this tangential contact effect when swinging with both hands instead of just the lead arm?
this made me think of how many people online talk about how ball position pre-disposes you to out-to-in contact with positive AoA ball position and in-to-out contact with negative AoA ball position – however I feel this again reduces to improper shoulder rotation and poor setup (reminded of your post on picking the ball cleanly, how even with a negative AoA setup you can pick the ball since the lead arm takes a hanging position defining the low point of the swing and the shoulders will pull the club upward from that setup point even if shaft lean is setup to be compressive at impact)
Correct on your points and observations, sir!
Correct, Kaushal – the swing moves the club in a natural arc without one having to do anything more than simply swing it. It comes from the inside, reaches 0 degrees, and moves back inside.
The problems occur when people try to manipulate the club path unnaturally.
Notice how, in the below swing, the arc is there, but it reaches 0 degrees in the middle of his stance, telling you right away that this is a Modern Golf Swing model being used.
Then you see all of the acrobatics involved when they are swinging the longer clubs, trying to reconcile a 0 degree arc point in the middle of the stance rather than towards the leading foot.