Bowling is not a muscle sport,most PBA bowlers weigh under 200 lbs,some of best weigh under 190.You don't look as stiff as you did in the 1st video. AT the beginning add a small knee bend and forward lean and keep it throughout the approach.
So with that being said here goes.
Setup - Tilt your bowling side shoulder down a little.you have the weight of the ball mostly in your right hand ,so if your shoulders are level in the setup the your raising your right shoulder.
2nd step- Allow
the ball to fall down towards your knee in the pushaway.It takes muscles to lift the ball up in the pushaway.
3rd step - (Remember small knee bend and forward lean)You look a little stiff here. When you allow the ball to drop in the pushaway you must keep a long 3rd step so that the ball will be behind your leg (yellow circle)at this point.
4th step - More forward lean here. Most pros have their balance arm forward not up. When you get the pushaway down , long 3rd step , step 4 will be short.
You look good at the release point. I can't think of a pro that follows through like you (I'm sure there is someone).
Here is your homework.
work on the forward lean and lower shoulder then work on the pushaway,get it down then take a long 3rd step.
Work on one thing at a time!!!