Lasse,When I get time, I'll shoot a better one,
When you do it would be better to position the camera directly in the path of the line on the forward cast. That might present a problem in the line hitting the camera, but would get rid of the oblique angle that will affect the angle measurement for the casting plane.
Better yet would be to have a 6 degree of freedom sensor attached to the rod so you could get real time 3-D measurements of the butt path like they do for golf swings.
It appears to me that you bring the rod more in line with the casting direction at the end of the cast and that would make the rod appear to be longer when viewed from a camera positioned perpendicular to the casting direction.
The result that is giving Merlin problem in the measured cord length values is that the cord length at MCF appears to be longer than it was at RSP1 when the cast was viewed from the side.
Hard to tell when the rod was vertical in your video and the oblique camera angle will affect the tilt measurement, but it appears the plane tilt in that cast was around 30 degrees
That would produce a foreshortening factor of cos(30)=.86 (36 degrees would be .81) which gives Merlin problems in comparing measured data with the predictions of his 2-D model.
Gordy