"It is imperative to remember that the path that the rod tip takes is the path that the fly line will follow."
"Remember that the line always follows the path of the rod tip."
This is what we have been told lots of times. This experiment shows that things don't work exactly in that way.
The "line follows the rod tip" rule of thumb is A GOOD ONE FOR TEACHING, but it isn't how fly casting actually works.
For a video showing this same effect but on an actual fly rod, fly line and fly cast take a look here:
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