I took a typical weight lifting class for high school this previous year, but my deadlift by the end (1 semester/4-5 months) was only 315 lbs I think, maybe a bit higher... but no more than 15 lbs higher. Anyways, deadlift wasn't a strong lift for me, I didn't like to do it nor was I very good at it. I was able to achieve 300 lbs in squat and 190 in bench. To me it looks like you aren't using your legs enough, looked like you extended your legs initially and then did the rest of your lifting with your back. Whenever I did my deadlift I think I used more legs, I squat down a bit more than you. I would ask some other people for tips. I would just say work on your form though, good luck!

Ask Motivational, he would be able to help you a lot more. Sorry if this didn't help or I was just wrong. Again, good luck.

Yeah, I feel like im using my back more than I should, but it's not as bad as i seen other people only use their back. It was in the moment so I'll try to use my lower half! Thanks though I appreciate it. As you watch does it look obvious too much back or is it more sly?

The deadlift uses the majority of muscles in the body, althought most of the strength required comes from the legs, back and core.

Increase your back, leg and core strength and your deadlift will improve. You can do this by just practicing deadlifting or by using isolation movements for different muscle groups. Surprisingly enough, the squat revolves around almost the exact same muscles. If your max squat is a lot lower than your max deadlift, bring it up a bit and it should help you a lot.

Your weight is one of the most important factors. The more weigh, the more of an advantage it is to you. Bulk up and gain weight and your deadlift will increase hughly. Bigger hands, bigger bones. There's a lot of advantages from gaining weight.

You can also use more equipment if you're more focused on increasing the weight, as opposed to increasing your strength. For example, you could use chalk, wrist straps or even powerlifting shoes.

To wrap it all up, keep deadlifting, eat big and do isolation movements. There's honestly hundreds of things you could do to increase your deadlift but I gave you what I consider to be the most important ones above.

Nice lift BTW, you used good form and that was an impressive weight.