I've got a bad back too and while i had many indicators of herniation there weren't enough for a diagnosis. From experience with lesser injury i can say don't let up on core rehab for stomach (especially deep stomach muscle it is a pain reliever to the max), back and the sides if your hernia was in the lower back. Aren't most of them there? Also please please do take it easy in throwing. A doctor specializing in back issues said to me that such a sport shouldn't exist from medical perspective because it is too rough for the back and other places. Grr
Unfortunately your throw had a trouble with your back and the remedy is to stress the back more so i feel hesitant to mention it because i you wanna improve and doing that means pushing your back. See your core muscle were too loose and you tilted to the front and left at the hip. So this was not a successful throw form wise and therefore it is hard to say what your good throws look like and giving advice based on this throw may lead you astray. I'd like to see another throw that doesn't move as fast and stop the right leg in place rock solidly. This ain't javelin throwing so "junttaus" in Finnish is out. At least for the latter half of the time between the plant step foot landing and the disc ripping out. The earlier part may benefit from stopping the leg hard in place for a while after you've moved to the right heel with the right ball of the foot high off of the ground. Now the whole sole touches the ground for too long and that is hard on the leg and the back and very dangerous to the health. Especially if the right foot pivots into an obstacle that stops the foot in place.
Considering how you need to guard your back i'd concentrate on keeping the arm muscles very loose and maximizing the speed of the elbow straightening. The command the brain needs to send consciously to the arm is to straighten the elbow as fast as possible. Not as strong as possible as if you were lifting weights. This is a speed sport so the movement speed has to be maximized and given your health issues the arm chop is the safest place to improve in. Because it has room to improve in the explosiveness of the acceleration.
You moved from rear right to front left and threw a hyzer. That ain't the most accurate way to throw or the most powerful. For max accuracy see my signature. For more power the steps should be curving from rear right to front center to a little right of center with the first, x and plant step. i recommend against power throws for now because of your back and get as much accuracy and consistency first. Disc golf is an accuracy and consistency game first distance third. Climo never threw as far as the farthest throwing competitors but still he took 12 world championship titles.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.