At the beginning you look to be a little broken at the hip.
One aspect you want to start looking at is cadence.
You need a minimum cadence of 90 for ground reaction force.
It doesn’t look like your heel is kissing the ground. This is an important aspect so your calf is not contracted the whole time you are running. At shorter distances your body can probably buffer it so you may not be aware of the situation.
Here a video of Nate Helming, SFCF& Helming Athletics
http://www.helmingathletics.com/2013/11/03/do-we-really-fall-when-we-run-2/
If you need drills or anything let me know.