If I was just tapping it then the weapon wouldn't stay over my head when his sword comes down on it. The combat is fast paced and I don't have the luxury to hold left block for 10 minutes, I'd be dead in less than a second.
Wrong, you'd be dead if you dont hold your block to whatever attack he has when he's in range.
Delayed attacks are one of my fav things to do, when someone moves even the slightest bit from their correct block, either to attack or miss block for whatever reason, I let go of my swing, and bye bye, right through the animation some times, even with shielders. It has nothing to do with being OP, I do it with 1hers, & pole arms too, it's a technique.
Go to the duel server, practice with good players, you'll learn.
& actually I just said that about LHB because you said it about 2h? see how stupid it made me seem? now see how stupid it makes you seem. xD
Classes are really balanced at least to me, just my opinion, but I know that 2h doesn't specifically go through blocks & by watching the video you posted I see what you're doing wrong I don't see anything OP or glitched or anything.