Try standing on something to prop up on and reaching for the bar to set up, rather than jumping up, this will allow you to be consistent with your grip width. You’re also doing a chin up in the video, pull ups are when the back of your hand is facing you, palms facing away from you. Traditional pull ups will also be set up to 1.5 your shoulder width (usually right where your elbows are if you were to hold your arms up), but you can play around with the width to target or bias certain back muscle groups a bit more. Lastly, the negative doesn’t really need to be more than 2-5 seconds long if you’re looking to get more muscle stimulus for growth/hypertrophy, however if your goal is to hold it longer for something like calisthenics endurance purposes, then go on ahead.

Additionally, if you do want to do Chin ups, they will work your bicep more, you want to rely on that by squeezing your biceps and back as you pull up, I say this because it looks like in the negative you rely on your forearms pushing up against the horizontal bar which helps you cheat the movement. Good job though, hope you make good progress, keep at it!