Regardless, I have learned that the truly influential casting aspect to focus on instead of "rod load" is in fact "line tension", even though the condition of rod load is an indicator of the status of line tension. So, if "tension" is substituted in for the term "load" in "constant load", then the vid shows that in all casting sequences except #6, the line stays taut/tensioned throughout the Sweep-to-Forward Casting Stroke sequence.
If one adds the concept of line "momentum" which can be substituted for "tension" it suggests that when the line is being powered by the rod ("in power") the line follows the rod tip as momentum is created. This is most effective during a straight rod tip path.
During a brief pause or change of direction of the rod tip when power application ebbs, (briefly "out of power") the momentum which has developed allows the line to continue following the rod tip. The "momentum" created keeps the line in "tension."
This is why the tempo of power application is so important in smoothing the casting sequence.