With the elbow thing I am trying to follow her head, am I doing it incorrectly?
^ Nope! You're getting the hang of it! Your wrists look rather stiff and like you are bending them outwards slightly though. You're doing a good job at keeping your thumbs on top, but just relax your wrists. Perhaps try quieting your hands down a bit, even glance down occasionally to see where the horse's head is at until you get a feel for what the head is doing.
I noticed that your arms were moving quite a bit because you look a tad stiff in the saddle. I do this too. It's almost as if you are trying too hard to be correct/right and are therefore not relaxing into the ride. I don't mean relax as in slouch around, but more like allow your body to go more with the motion of the horse. You do look quite a bit more relaxed in some parts than others and you are doing a great job of trying to sit up correctly!
You seem to be sitting a bit far back in the saddle and perching a bit on your girlie bits. Your backside should be in the deepest part of the saddle. Try sitting more on your seatbones.
If anything I think you should shorten your reins a tad and carry your hands forward more (not too much though!), but still without breaking that bit, hand, elbow line (which I thought you generally did a good job of maintaining!).
I quite like your leg position, wish my leg would just hang like that! :)
I agree with justjump
about bringing your shoulders back too.
Can I suggest encouraging her forward more with your legs and holding more with your hands? She's currently not tracking up in the walk - let alone over-tracking. She's lovely and calm though.
Here's something different to think about - I recently had an excellent dressage coach teach me that you shouldn't physically look ahead for your next movement (I know, I was shocked too!). By all means, prepare for the next movemet though. You should know exactly where you are in the arena, know the test extremely well and be able to prepare without looking too far ahead. I lost track of how many times I had "WHERE ARE YOUR EYES!? LOOK BETWEEN ZE HORSES EARS! YOU ARE NOT SHOWJUMPING!" yelled at me, haha!
I hope that helped a bit and that I wasn't too confusing/nit picky for you - I tend to get carried away when doing critiques! :) I do think you are a lovely rider with a really cute horse