1) Foot strike to far in the front as in [1] and [2]. This mostly happens because people want to run fast, and therefore take longer steps. It is very counterproductive though. A longer steps lowers your center of gravity, and because the foot strikes the ground very far in front of the COG, you need to lift your COG before you can do the next step. This is visible in the video of the article as well. The amateurs have a much larger vertical movement of their heads and torsos than the Freeze.

2) Insufficient leg extension at the end of the ground contact as in [3] and [4]. There are two reasons for that. The first one is connected to the point above. If you keep the COG very low, you are forced to bend the hip and the knee while you move your torso over your foot. It's very hard to extend hip and knee after that, so many people just lift the leg instead of pushing all the way through. The second reason is mobility. Sitting all day shortens the hip flexor muscles (M. iliopsoas). Stretching them helps a lot.

Many of the people in the video are also starting quite fast and get considerably slower over the course of those 160m. Tiredness might be an important factor there.

[1] Bolt, foot strike: https://imgur.com/a/QOQaEX2

[2] Amateur, foot strike: https://imgur.com/a/Pmiijgx

[3] Bolt, leg extension: https://imgur.com/a/mRCq7uc

[4] Amateur, leg extension: https://imgur.com/a/cxzMkEi