Looks like a wrong contravention to me, if they'd issued it for going through the no-entry signs at the entrance to the road you would have been in a spot of bother. But they didn't and it's too late now, so a simple challenge should see this off:
Dear London Borough of Hackney,
As the video clearly shows, I reversed into the Greenwood Road and then turned left. I never went past the no-right turn signs seen in the video and in any event, I never turned right.
It follows that the PCN must be cancelled.
Yours faithfully,