Your miters came out perfect! What I do when I do mine is to sew the 4 borders like in the video, but then I lay the corner out on the ironing board and over lap the pieces, then I fold one back to 45 degree angle and glue baste it, then I open it up, pin it well and sew on the crease. After I sew it and check it to be sure it lines up, then I trim it. Works perfect for me.
