Clip 1 – 5 November 2018 - Law 11
From a tackle, the ball comes back to Ben Youngs, the England scrumhalf, who kicks a box kick. Aphiwe Dyantyi, the South African left wing comes forward.
He knocks on under pressure from, Jack Nowell. Pieter-Steph du Toit of South Africa and Dylan Hartley of England are in front of Dyantyi when he knocks on (In front in the sense of nearer the England goal-line). Du Toit and Hartley are in close contact. When the ball flies forward from Dyantyi, they both try to grab it but Du Toit wins possession. The referee penalises Du Toit.
It was clearly stated in the pre-abbreviation laws:
Law 11.7: OFFSIDE AFTER A KNOCK-ON
When a player knocks on and an offside team-mate next plays the ball, the offside player is liable to sanction if playing the ball prevented an opponent from gaining an advantage.
Sanction: Penalty kick
There has not been any change to that law. There has been no clarification altering the law.
And so Du Toit was correctly penalised and England garnered three points.
As a matter of interest, have a look at England's tighthead, Kyle Sinckler, when Youngs kicks the ball. He gives the impression of being offside. Presumably, that is an error of parallax as neither the referee nor his assistant deemed him offside.