I started an apple core years ago and found sewing the shapes together was easy. Someone told me the best way was to put the convex shape on top, which worked quite well.
However, sewing the rows together was a pain with this method, because every other block in a row of blocks is convex, and it's not very practical to sew a block, then pull it off the sewing machine, flip it around, then sew the next block, pull it off the sewing machine, flip it around, and so on. So in frustration, I wadded it up, threw it in a corner, and pouted.
Does Jenny's video address the assembly issue at all? My work computer doesn't have speakers.
Maybe I should dig that project out after all, it might make a great hand-piecing project to watch during football games.