I am working on this block too. I found a different video which helped me a lot. Maybe it will help someone else.
The block is assembled as a four patch, which just makes more sense to me. You get four corners (A+B+C each) and then sew them together.
I am not using any pins most of the time. When I do pin, I pin ALONG the seam line from the bottom of the seam up and taking just a tiny bite with the pin. I don't have to remove the pin until the needle gets to the very tip of the pin, then I can ease the pin out one stitch at a time if necessary. The pin is parallel to the the gap between the presser foot toes, in other words, with the head of the pin towards me.
My struggle now is to actually attach the blocks to each other and match the points.
https://youtu.be/iDwMSsRt5Xw?si=8GypB-OHRpz1KGdT