Pool ball analysis

One of my students is doing his IA on the relationship between the perpendicular distance between the direction of a pool ball and the centre of a ball that it hits and the angle between the original direction and the direction of the ball after being hit. That's a long research question but easier to see on a diagram. The student has some videos but measuring the lengths and angles is slightly problematic. LoggerPro tracks video but isn't good at placing parallel lines and measuring angles. GeoGegbra won't track video but is good at the other stuff. So, I worked out a way of using both applications. It's a bit complicated so I made a video.