Clip 4 – 4 April 2019 - Law 18
Melani Nanai, the Blues' fullback, has the ball and is shoved into touch. Nanai stays on his feet with the ball in his possession. Dillyn Leyds of the Stormers, one of those who put Nanai in touch, is also on his feet.
Clearly, it will be the Stormers to throw the ball in from touch. Presumably, to have the option of a quick throw-in, Leyds tries to get the ball from Nanai who refuses to give it up and appears to strike Leyds a glancing blow on the cheek.
Nanai drops the ball and walks back into the field of play where the referee says to him: "Let the ball go." He says it twice, a lineout is formed and the Stormers throw in.
There is a law governing what happened.
Law 18.3: QUICK THROW
A player who carries the ball into touch must release the ball immediately so that a quick throw may be taken.
Not letting go of the ball is an infringement. The blow to the cheek, while not powerful, does suggest that more than an admonition would not have been out of place.