Interesting video, and makes sense. Have followed Jenny's tut's on binding, and had no issues regardless of the backing material. Tight, a tad, but I usually pin in several places to make sure it's where it should be. 2.5 inches is what I go with regular binding, unless I'm using a false piping technique.

http://www.lvqg.org/media/2a7a5a699c...02ffffe415.pdf

And I totally ignore the part about "bias" binding, just cut WOF and run with it, either flat or utilizing the seam to create a "stuffed" piping look, it works great.

Leah, I use low loft as well, don't think you made a goof, but the video makes great sense regarding less bulk, especially at the mitered corners.