That video was full of wrong. Slack tow lines, loose octos floating behind them, piloting the BT like it's a Yamaha 2 handed scoot.
With the blacktip I occasionally use the shroud to help stear when I'm in a cross current...
For towing a second diver I use a handle on a rope connected to my backplate. It goes to about mid calf / ankle so the 2nd diver is slip streamed and not in the way of my fins. The handle is also connected to a gear keeper that is longer than my rope. This keeps it up and out of the way until I'm towing and then the rope takes full weight of the tow. Having them hang onto your tank or calf just makes things awkward.
Pics are of the handle my buddy uses (I copied him)
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