You have a higher success rate than I do. I only see 2 out of my 80+ digital copies shown up in the purchased section, although if I clicked on the "purchased" tab under the "store" section on the left of the iTunes software window, I see all of them, but couldn't re-download any of them again.
Worse of all, I've already thrown all those digital copies redeem code slips that came with all my Blu-ray purchases as I thought that I'll never need the codes anymore after redeeming my digital copies previously.