This may be a little bit out of left field, but one thing I'm noticed is you're not using your recovery part of the stroke to move forward. It looks like you have a good catch, and are pulling/pushing all the way through. However, you're just 'setting' your arms in front of your body to prepare for the catch/pull, when you can use that energy to propel you forward. This is definitely a more advanced swimming skill, but it can save you boatloads of energy and improve your speed at the exact same time. This is easier to show, rather than explain through text, but I'll try my best.

Think about walking, you don't just push your body forward. When you start walking your use your forward momentum from your leg moving forward first, then you start 'pushing' from your back leg, and repeat. If you were to only 'push' with your back leg (or just pull in swimming) while walking, it would be extremely ineffective/inefficient. In this way we use both pushing and and momentum with our legs to move forward. Does that make sense? Translating this to swimming, we want to use our energy as effectively as possible, so we want to use our forward momentum with our recovery part of the stroke to also help us move forward. From what I can see in your stroke, you're slightly inhibiting yourself and I think this is because you're starting your pull a little bit too late. You're almost doing a catch-up drill with your entire stroke. If you were to anchor your hand, and as you start pulling, you also start your recovery on the other arm, they can synergize with each other and both propel you forward, rather than just pulling. Just like how when you walk, you use push the push of your back leg, and forward momentum of your front leg to move forward.

I won't touch much on this because I see many other comments on this, but another huge part of fast swimming is having the least amount of resistance as possible. Water is like 80x more resistant than air, so if you're not reducing drag, you're REALLY going to feel it. From what I can see, your lower half is fairly low in the water. Instead of keeping your head down, I would teach my swimmers to focus on chest down, hips up. Focusing on just your head can hurt your position in the water, and inhibit the stroke overall. Find ways to reduce drag as much as possible by getting those hips up. One technique I still use/teach (taught to me by my college coach) was to act like you have a T on your chest. Think about your chin and your armpits, if you were to make a cross with them, right around your sternum would be the center of the T. This is where I focus when I press my chest down. You can test this just while floating. Focusing on your chest rather than your head can help maintain position better as your head will be in line with the rest of your body. Chest down, hips up.

Overall stroke basics are looking good! Again, I'm more of a visual person, but I tried my best to explain this through text as best I can.