I noticed 2 things in the video:
You’re starting the lift in a dynamic fashion, as opposed to a static fashion.
You started the lift with your chest parallel to the floor.
I don’t think either of these is necessarily a bad thing. Everyone has their own style and their own unique form that works for them. Eddie Hall (deadlift world record holder) plays with the bar a little by rolling it back and forth before he begins his lift. If you continue practicing this style, it will work for you. Overall, this is not really an issue, but it does tie into my next point.
Starting with your chest parallel to the floor isn’t inherently dangerous. However, it appears that your legs are stronger than your back (as is the case with 99.99% of humans). When combining a chest that is parallel to the floor with a back that can’t adequately compensate for that starting position, it leads to a rounding of the lower back which actually can be dangerous if you start lifting enough weight. You know, herniated discs and all that.
Now, my advice:
For now, I would focus on trying to sink your hips and keep your chest up. Be proud of the chest you’re building in the gym and show that thing off! In all seriousness though, sinking your hips and keeping your chest up puts your back in a much safer and stronger position to begin your deadlift.
One good cue that I’ve heard from Layne Norton is “wrap the bar around your shins.” This will do two things for you: first, it will help you show even more of your chest. Second, it will engage your rear delts, lats, scaps, and traps. This is crucial to keeping a neutral (safe) spine position.
The first time I deadlifted using this cue, my upper back was incredibly sore the next day, which is proof that it works in engaging the upper back muscles. My final tip is this: start from a static position. No, I’m not purposely contradicting myself, but as Jim states in his original 5/3/1 article, the point of 5/3/1 is to take 2 steps back, and 10 steps forward. It’s easier to focus on perfecting your form with a more simple set up.
You’re lifting a good amount of weight, man. You’re doing the right thing by coming to the forums for advice. Good luck on your deadlifting!