That's certainly a good data point in the 'against' column, but it really only indicates that any current, if present, isn't likely to be caused by the normal circulation of water from filtration systems or similar. There are a number of other things that could possibly be causing a current.
For instance the current could be caused by the interaction between the pool and the motion of the swimmers in the pool. It could be caused by the overflow wave from 8 people entering the pool. It could be caused by uneven gutter heights leading to the pool draining at a faster rate on one side/corner. It could be a combination of all of these things, none of which would show up in a static test like the one they demonstrated.
The fact that this has happened at some races and not others, and the ones it looks like it has happened at are Myrtha pools, is interesting in itself.
Those tests are with floats. That may be the standard but it isn't appropriate imho. Swimmers do not swim in the top few inches of water. They swim as deep as four feet in dives, and are constantly dipping hands feet down two or more feet. Any current down there would go undetected by such a float, especially when it is surrounded by lane ropes.
Do a test with something hanging below the float, below the protection of the lane ropes. Or drop some dye in the water.
(I'm a little surprise by the wave action visible in these tests. With so many ropes, that water should be like glass very quickly.)
There is some theatre here. Swimmers know the water moves, that it isn't a stationary tank. A perfect pool, with perfectly still water in every lane during an actual race, isn't possible. As slight winds can affect football games, swimmers just have to live with slight inconsistencies between lanes and pools.
For instance the current could be caused by the interaction between the pool and the motion of the swimmers in the pool. It could be caused by the overflow wave from 8 people entering the pool. It could be caused by uneven gutter heights leading to the pool draining at a faster rate on one side/corner. It could be a combination of all of these things, none of which would show up in a static test like the one they demonstrated.
The fact that this has happened at some races and not others, and the ones it looks like it has happened at are Myrtha pools, is interesting in itself.