I think it is really cool you are here getting advice on your own. There are some great suggestions above. I would like to add one thing I learned at another site. When taking infield/outfield you don't have to be in that exact position every time. Instead of running back to your original position every time after you field and throw the ball; have the person hitting you grounders/flies hit another ball right after you release the throw. This will show more athleticism in your video. If you get a ball to your left, have the person hit the next one to your right. Have him move it around. Don't edit any mistakes, just keep moving on your toes.
Also, find someone really good to teach you mechanics and get a strength coach if you can afford it. If you can't afford it, find a way to get the best info you need. You really need to start now at this age. Don't wait. Last thing... play in a lot of games. Learn to be a player/winner.