A couple of observations ......... for what they're worth!!
It's an odd dichotomy that you have minimal or slow momentum to the plate but at the same time you are very 'out in front' on release. This tells me that you have alot of good stuff to work with. Your natural motion is to release when you are out over your front foot. However you are slow getting there. To me, the most important thing you can work on, and this also considers your previous video, is to increase dramatically your forward momentum. To me that's by far the most important thing for you. Am I repeating myself? Must be important then!!
Secondly, you may have swerved into a sage point! Throwing is extremely important. One thing that came out of a recent NPA meeting was this quote from Tom House, "Kids these days pitch too much and don't throw enough." Throwing, playing catch, is a fabulous way to strengthen your arm. It is also, as you say, a great way to develop a good throwing and pitching motion. But it also, most importantly, helps develop proper timing and sequencing of release. Keep doing that. It's important too.
Regarding arm motion. Leave it alone. It's fine. It's part of your 'kinematic sequence signature' as the NPA likes to say. Arm slot is what it is. The important thing is momentum, timing, and sequencing of events that lead to explosive release. One thing at a time, though. In order to evaluate those other things, we need to see you from a mound and at more intensity.
Keep it up, you've got alot of good things going for you!!