You look like you are enjoying yourself! That's great!
Brutus has amazing scope and bascule and he's really cracking his back over these fences. I love, love, love this guy.
However, his powerful jump is affecting your position and partly causing some of your problems. On a thrusty horse like this, it is difficult to keep a nice steady position as opposed to a horse who jumps flat.
You've lost your leg and its slipped to the rear (may be as a result of your stitches). Sink your weight down into your heel to anchor your leg at the girth. You will have to really concentrate on keeping that ankle flexed and heel down, because your horses powerful jump has encouraged you to turn your heel in and use your lower leg as a gripping hold instead of a soft, supple hold.
Once your leg is on, you will have a steady base from which to folow your horses motion. His thrust has popped you out of the saddle, sending you onto his neck. Sit and wait for each fence, I would suggest staying in a three point contact instead of a two point to discourage any run outs. Trotting lots of fences will help.
As for the release... its really nice. I think the reason your hands are so high is because your horse really uses his neck over each jump so it seems to disapear as he lowers it over each fence. This makes it harder for you to keep your hands on his crest.
I would discourages trying to use an auto release (straight line from hand to mouth) until you are more stable in your base. Right now, a long crest release will be sufficent and provide you with support and your horse with the long rein he needs to round over these jumps.
High hands will not stop a horse from running out. If anything, they will create a tight, punsishing grip on his mouth. I suggest you do alot of work at home with guide poles on each side of the fence to prevent run outs.
Keep your body straight and look to the next fence. If Brutus is sensitive (and I have a hunch he may be) he will feel if you twist in the saddle and he will anticipate a sharp turn. Keep both legs on and use your legs and seat to keep him straight. Too much hand before or after a fence and he will resent jumping.
Good luck!! I hope you feel better soon!!!