Too much emphasis on the motion up to the right pec.
Too little emphasis after the right pec position.
If you want to start to improve you need to get rid of some of the "noise". You have lot of extra motion, loops, and hitches going into the throw.
For a training exercise, I would suggest starting your throw with the disc firmly planted in your left pec. Then pull the disc into your your right pec and throw through the forward apex.
In otehr words, the disc goes in a straight line from the left pec, across the chest, through the right pec position, and down the arm. Keep you hand on the other side of the disc away from yourself as long as possible.
disc from the right pec to the target= straight line right at the target
Hand on the other side of the disc
Disc down the arm from the right pec
throw the disc down the line with the hand on the other side of the disc
"The reasonable man adapts himself to his environment. The unreasonable man adapts his environment to himself, therefore all progress is made by unreasonable men."
-George Bernard Shaw