What attracts the fish to the tube? The ladders work by providing some water that is going down stream slowly it is an obvious path. If there is no water to swim upstream against I don't understand why a fish would enter a random tube.
At about 88 secs in the second video[1] they show the inside of some sort of "trap" for the fish where water flows rapidly over a grate (and claim "volitional entry"). But I agree it's still an open question whether you could mitigate the fish's behavior effectively.
Salmon will swim towards turbulence (as part of a simple navigational strategy) so you can get them to swim into something using that. However, as with fish ladders, I expect it isn't 100% effective.
Source: my dad has built some fish hatchery equipment including volitional entry devices.
