Video analysis of hurdles requires a great camera, the use of Dartfish or robust video analysis software, and a good checklist of what to look for. I am not a fan of nitpicking and getting into take off mechanics with breakdown. The best way to see mechanical improvement is to see the results of the take off and focus on gross changes. I have seen an athlete go from 10.45 to 10.06 and only see 1% change in mechanics biomechanics wise but the video looked dramatically different and live running was night and day. To make things simple I have a checklist of 3 core changes I look for. I am not interested in splitting hairs or pretended to see the left femur radially swinging with elastic cofactors and other glory statements.
Hip Flexion/Extension-Does the front side mechanics improve? I look at less extension and less flexion at the hip. I just measure the change once a month.
Hand Height- The swing of the shoulders should be balanced and it’s hard to see how much is perfect, but arm length will often look like an athlete is over striding. Arc distance of the humerus is labor intensive and I just look at arm carriage decreasing with the second and third step over 2-3 hurdles.
Take off distance- Does the the take off distance improve or stay the same? Bunching hurdles will not be accurate and I like full distances for analysis. Make sure you are compliant with Ralph Mann’s distances. Take off distance is the simplest way to get feedback.
Other factors can be broken down but the three above are the most modified at higher speeds. Over the next few years I think we are going to see another wave of evolution now that we can sample actual timing splits and velocities.