Jerry, as far as I'm aware McDonald never claimed to be the officer that actually handcuffed Oswald, he certainly doesn't say that in the vid you posted, only that the cuffs were his.
Hawkins' testimony:
Mr. HAWKINS. They had a scuffle and I immediately ran to the location. Officer Hutson had come in the aisle behind Oswald and McDonald and Officer Walker had come in on the left-hand side and I came up in the front. I grabbed his left hand and then immediately
took my handcuffs out and put them on his left hand and we brought his right arm around as soon as the gun had been removed and handcuffed his right arm with both hands behind his back.
Hill's testimony:
We finally got the man subdued to the point where we had control of him and his legs pinned and his arms pinned. I said, "Let's handcuff him." And being that I was working in plainclothes and working in personnel, didn't have a pair of handcuffs, and I
asked Hawkins if he had. And he said, "Yes." And I said, "Let's get them."
And Hawkins and I handcuffed him while the others held him.