For an over weight Morgan he does well!
One thing I noticed as soon as I watched your video is around your turn you keep two hands on the reins and sit forward in your seat. Since you go to the right barrel first practicing taking your left hand off the reins in the right turn, holding the horn and sitting deep in your saddle. Same with the left turn, just switch hands.
On the second turn, you looked nice. You took your hand off the reins, but your still leaning forward on his withers through his turns. Sit back on your rear, push your heels down so you can balance yourself and also if you need to use your feet you have your legs ready.
I can't really see your third turn.
On poles, you can really either hold the horn, or keep both hands on the reins and grab mane with the outside hand. I find it easier on faster pole horses to keep both hands on the reins. That way you can have them there since they normally begin weaving on their own.
There's not much I can say about your pole run besides try practicing slower with moving his haunches out while weaving. You two look great.
Also while weaving, instead of pulling his nose to weave, try pressing with the outside rein and either moving his butt away from the poles with your inside leg or yield his shoulders in with your outside leg after your knee is past the pole.