One thing @dt79 is getting at is inconsistent form. There are better reps in here and then there are worse reps. Might do for you to take an extra second or two in between reps to hit all of your cues. What can help is to completely re-setup for each rep. Like stand all the way up and maybe take your hands off the bar. Every bad rep you practice grooves bad habits. It really depends on your goals though. Re-setting up for every rep takes additional time and is not going to get your heart rate up, however, until you've learned good motor patterns, it's probably more important to nail the basic mechanics of the lift.
Re-watch the video and look at the bar path. There are some reps where the bar path is relatively straight up and then there are reps where the bar goes out and comes back in. In your setup, you want your shins as close to perpendicular to the floor as possible. This alleviates two things: crooked bar path and wasted force. Every degree off of perpendicular that your shins are from the floor will add extra inefficiency in the movement.
Here's a good video where Brian Alsruhe goes through his deadlift.
The big thing about deadlift is that there are guys with great form that will never get past 3 plates and there are guys with shit form according to the experts that will pull 800+. You have to use the larger principles (straight lower back, perpendicular shins, tighter than you can imagine in the hole) and find out what works for you.