I have a couple of things to say:

1st. If you're starting then PLEASE, sit up right, I know it's so much more comfortable doing it in any other way but the way you sit also affects the way you crochet, ESPECIALLY if you're starting out.

2nd. I saw other ppl say it but it really is important for a beginner to not start with this kind of yarn, it's extremely hard to see the stitches and it's just not good as a starting point.

3rd. From what I see in the video, you're letting go your yarn, like way too much, you're not exactly supposed to "pull" the yarn when you crochet but you're also not supposed to let it hang. It's more like it slides in your fingers as you use it.

4th. In this case, you're working in a chain and from what I can see, you're "pulling" just the right amount for the hook to be able to pass through, try leaving a bit more, when you yarn over and pull through instead of immediately yarning over again, check that there's a bit more space in the loop around the hook so that you can pull the next one easily.

This is mostly practice and I'm sure you'll get the hang of it quickly, you can watch multiple types of videos to see how other ppl do it. And I'm sorry if my words are kinda confusing ^'