Round the side. Round the side of what?

The Crusaders play the Sharks. The Crusaders win a line-out and form a maul. The Sharks resist the maul but eventually the maul edges forward and goes to ground. The referee does not see anything wrong with the collapse of the maul. The ball is available and Ben Franks picks it up.

Franks moves to the left and three Sharks tackle him - Bismarck du Plessis, Tendai Mtawarira and Jacques Botes.  They tackle Franks.

There is no ruck - despite what the commentator says - and there is no maul. Franks is a free agent and a free target. Players are allowed to tackle opponents from the front, the back and the side. When Botes drove in on Franks from the side of Franks, he, Botes, was entitled to do so.

It does not seem that Botes infringed.