Firstly, what a cute filly!!!
Are you looking at specifically halter, or showmanship, or both? Halter judges the horse, her confo and way of going, etc. Showmanship judges you, your presentation. In showmanship, the horse is a "prop" to show your ability to groom, condition, and control the horse - conformation isn't nearly the factor that it is in halter (in fact, in the 4-H rulebook for my state, I don't believe that it's a factor at all.) There are some other more subtle differences as well.
I would say that, if you're showing Halter, your filly will be judged according to the standards outlined by her registry. I'm not terribly familiar with minis, but if you look up your registry's website they probably have a list of what the ideal is for minis with their registry. That is what she'll be compared to in the ring.
I'm not much at critiquing, but I recommend posting in the critique section to perhaps get more nibbles on those questions. There are some very knowledgeable confo-gurus here, as well as a few people with a lot of experience in buying, breeding, training, and showing minis.
(Watched Video) Something to watch for when you're leading her for showmanship/halter - make sure to keep your body about even with her throatlatch; you get ahead of her a few times. Your turn is into her, which is good, but it needs to be more of a pivot. Making a right turn into her, her right hind hoof should be planted, and her left hind should step around the right. Her left fore will cross in front of her right fore.
Show attire depends on what discipline you want to show (English or Western). English, you would wear jodhpurs or breeches and tall boots, ratcatcher shirt, and hunt coat, with helmet or hunt cap. Western, you would wear slacks (slightly fitted - look up some pics on Google to get an idea what to look for; Some companies actually sell "official" showmanship pants), boots the same color as your pants, a belt, and a western type shirt or blazer. And a cowboy hat, of course.
At the beginning level, walk/trot/back/set-up/pivot/halt is enough to get through the patterns. They do get more difficult than what you describe, but if you have the components mastered, it isn't too bad at all.
The big thing that might be added to higher level patterns is a pull turn, but you can cross that bridge when you come to it.