How does Dead Angling work?

So, I've watched the video a few times. And I've also even managed to do it a few times.

I thought it was when with a weapon with a wide arc, you attack in a direction not facing your opponent and it bypasses shield block. Now I've tried this and I can't seem to get it to work. I have managed to get a few really crazy hits through the Balder Side Swords R2 lunge, where I'd hit just to the side of the person I'm aiming at and it has bypassed shield block, I didn't realize it would be possible with the lunge. That's the only time I've ever gotten it to work though.

Would it be possible for someone to break it down for me a give me a scenario or a step by step way to get dead angling to work for me? I've tried with the G-scythe lately, and I was told its one of the easiest weapons to get it down with, but the only time I've been able to achieve a what would appear to be dead angle would be with the BSS.

Its experimentation. weapons and attacks all have their own angles it works at. If you can get a buddy to practice with base weapons, try that.

Its easy with horizontal sweeping attacks, and even easier without lock on, just need to practice

You have to hit their side.

Playing without lock on is the easiest way to do it. Or horizontal while-dashing attacks against players who are strafing.