Well Done Reg!!! An xllnt accomplished build with not much for special tools, but rather oodles of skill! You should be proud!
Now to tweak the radio to get it running at optium performance!
Recap:
What voltage are you running?
Are your valve servos opening at 100%?
What size plumbing (ID) to your cyls?
What pressure were you running at in your last vid?
What was its finally weight tally?
I use the dual rates for the stick/bucket/swing, no such option on the dx8 for the throttle (boom) unfortunately, but can adjust throttle curve. I have the boom servo valve @100% for up, but approx 60% for down so the boom doesn't drop too fast. Using Dual Rates on the other three, you can tweak the valve openings for various digging operations.. like when loading a trk & don't want too fast of movement vs everything wide open for digging & piling.
I couldn't hear any pump esc freeze in any of your two vids, but it could happen with the brushless if rpm drops too low. I assume you have the pump on Aux 1 or 3? If 3pos switch is down to turn off pump, you could set the middle position to operate @10 to 15% so the pump rpm never fully stops. Then with the Mix on, pump with go to full speed with the servo valves are activated. With Mix off, pump will turn slow for more precise movements.