It would be better if the compression rate wasn’t so high on this video. It looks like the frame rate is around 15fps, there is two of you in every frame so it blurs alot. If you can get it to 29.97fps it will look much better. Also more direct 90 degree side views would be better to see the angles, especially if you set the camera 90 degrees to your blocks for a few shots.
First fix your set position:
Your hips are too low, leading to your feet not being in full contact with the blocks as others mentioned. You have too much weight on your hands and not enough on your feet. They all go together.
When you go into set shift your hips up and back so that you get your front shin to approximately 45 degrees with the ground. Your shoulders should be directly over your hands and not leaning far over the line. If you draw a line down your front leg shin in set, it should point to the middle of your shoulder. If you drop a plumb line from the center of your hip, it will point down to approximately the tip of your front toe. Your front leg knee should be around a 90 degree angle and if you draw a line from the center of your hip through the middle of your knee it would point to your hands.
At the end of your extension off the front block you should be in a straight line from your ankle, knee, hip, shoulder and ear and that line should be 40-45 degrees from the ground. Because your shin is at too low of an angle, you are not able to extend all the way out, you’d land on your face if you did. So you cut short your extension and round your back. Your foot doesn’t get off the ground much and lands a little too far in front of you so it leads to a rather soft ground contact and your foot has to wait to get under your center of mass to push, instead of being above the ground higher and hammering through it reactively. You should see full extension just like the first step for 6-8 strides before with each step increasing in angle until you are upright. It gradually becomes more cyclical after the first 6-8 strides and the knee won’t be fully extended at toe-off.
Be careful that you don’t drop your shin off the start or you will kill all the great angles you set up. To prevent that you might think of pushing through the middle of your foot instead of the ball, or imagine your front shin cemented in place and pushing off it.
With the technique you have now, it might not hurt you too badly in the first 40m, but it’s so much harder to get into the right body positions when you get up to max velocity mechanics. If you do it right you’ll get alot of lift at 35-40m and everything is easy from then on, just just stay relaxed and relexive and emphasize downward pushes into the ground rather than pushes behind you late in the stride.
Check out the pictures of King Carl that I attached, or the Bolt pic.
You are very powerful and dynamic, I’m sure you run a good 60, but I think you could be alot better 100m runner if you could make some corrections with your starting mechanics.