I just watched the video myself. And I agree with you. It's messy. The points are super cut off.
Some quick piecing techniques are like that. They just don't turn out perfectly. And it's not you, it's them.
But the nice thing about this quilt and about quilts in general is that when you step back, you really don't really see it. Looking at the quilt prior to her piecing, I did not notice the cut off points at all.
I personally would prefer to do a well-done square in a square quilt. It would be a good use of scraps too. And the result would be the same as far as creating that shimmery exploding look. But if you just want to sew and have fun, it might be a fun technique to play with, especially with pre-cuts, since it's sometimes hard to figure out what to do with them.