Hello and welcome to HF and to western riding!
I can't answer the question about wild horse behavior videos with proper narration as to horse politics and hierarchy, language, etc, but I can recommend you watch Warwick Schiller. He has many videos on youtube and explains domestic horse behavior, reactions, and 'language better than I think anyone can. He's rather matter of fact about things, he's an Aussie so he calls it like he sees it and very forthrightly so but he's never hateful or tacky.
I strongly recommend binging on his videos, but also spending a lot of time in the company of horses, both in a group and alone and simply observe. Horses are very talkative. They're very expressive. Some are quite verbal. They are individuals within a herd with very distinct personalities, histories, and hang ups. They are also very honest - horses don't lie. They don't pull punches to save human pride and preserve human ego. The best thing I've ever done in my understanding of how the horse talks to me and how they behave is to simply crack a beer open, and sit in a chair outside my tack room, and watch them in the pasture and at the feed trough. Learning to speak their language and learning to listen to them and speak back will be one of the most rewarding things you can do... and doesn't even require a saddle.
Wishing you the best of luck on your endeavor! Enjoy it!
"We are here to laugh at the odds and live our lives so well that death will tremble to take us."