This is what a video battle report should look like.
Slightly hard to follow as it goes pretty fast. But damn good. Immersive. This is the essence of what 40K is to me - the not-so-competitive player - I want that story, the emotional investment in your little dudes and what happens. If you don't care - then what's the point? Winning? Congratulations, all that time spent for a very fleeting feeling of smug superiority. I'd rather have a narrative, but maybe that's just the original Drakar & Demoner RPGer in me speaking (very old GURPS-style, iirc, Swedish-language RPG I played a lot back in 1988ish).
So how, la?
Tripod. Or steadicam. Some basic editing. Some sound effects. And a bunch of planning ahead of time. It's really the planning that shines in this video.