To eliminate the pt. problem, lay the 45 degree line of your ruler on the long cut edge of the fabric, not on the sewn seam. The top point of the ruler should be on the stitching line at the top.
If you use two 2 1/2" strips sewn together, your sewn strip is 4 1/2" wide. (the video says 4 1/4" but NOT)
If you use the width of the fabric on the 2 1/2" strips you should get 10 cuts (HS triangle blocks). So you'll get 2 complete blocks with 2 extra cuts. I thought I'd use my extra cuts in the borders somehow.
I've been sick for the past 10 days but will try to get some pictures posted back on the original post.