Discovery of an area I need to train

17 years ago, I tore my hamstring breakdancing and was misdiagnosed by the Navy doctor. I suffer from knee pain and did not know why but after doing research, I think it is because I have weak hamstrings. I believe this is why I can sprint easier than I can run distance because I can lift my knees high, but this places abnormal pressure on my hip flexors and core and I am dragging the rest of my leg through the stride. It is equivalent of doing "high knees". I found some great exercises that I can do to blow out my hams and glutes and today, I am going to stretch (I might do arms and shoulders) and on Saturday, focus on blowing out my hams and getting them strong enough to where I can start running again with a purpose. This exercise looks like it does the trick and I have never done it before.