I will try and give my take it on it, but I would also recommend what todday would say if he's online or acole or other people would say.
I have to admit I was looking at videos a few times, I see what you are doing wrong, but trying to find out why, like what part of the sprint you are not doing right, ok lets move on.
First lets look at a slow mo of a proper sprint start. Keep an eye from start to 2 seconds and compare with yours.
<![CDATA[<a href="http://www.youtube.com/watch?v=p9zyVdrI434" target="_blank">http://www.youtube.com/watch?v=p9zyVdrI434</a>]]>You seem to be stepping out of the blocks instead of pushing, which should be your mental cue, like in swimming start where they push against the start platforms, in sprinting you push against the blocks to accelerate out of the blocks and use that to help increase your speed.
Also you seem to be leaning alot that you try and push parallel to the ground and therefore it looks as if you are stepping out (check your video from 4 to 6 seconds) and not (dont want to use exploding) pushing out of the blocks.
You want to be at an angle like in the video I posted, but dont think about the lean, let the lean come naturally and just focus on pushing out of the blocks.
Some drills you could do are the wall drills you can increase difficulty if easy by adding bands to your feet maybe.
https://www.youtube.com/watch?v=Wl3NO6eGQTwYou could do up hill sprints, not to steep and not to low, enough where you can run up it without slowing down alot.
Sled drags are also helpful in setting your body in that lean position or tyre drags.
The main thing to focus on is the lean and the drive out of the blocks.
hope this helps just my 2 cents
