Harry potter and felix felicis in book 6?

I'm looking at my copy of HPHBP now, Chapter Nine, "The Half-Blood Prince" (page 178 in my edition), and Professor Slughorn doesn't mention another student taking felix felicis.

"Have you ever taken it, sir?" asked Michael Corner with great interest.

"Twice in my life," said Slughorn. "Once when I was twenty-four, once when I was fifty-seven. Two tablespoonfuls taken with breakfast. Two perfect days."

I'm not sure whether this comes up later; here's a bit of history on it

http://harrypotter.wikia.com/wiki/Felix_Felicis

I think both Lily and Snape were good at Potions; I'm sure Slughorn would have mentioned it if either had used it.

This is only in the movies, no such thing has ever been mentioned in the books.

However I'll still take a guess at who that person could have been (even if it was only in the movies)

My bet is on Snape.

Harry wasn't noticeably good at potions, and won merely because of the instructions in his potions book. The person who wrote the notes in that book (Snape) would most likely have tried to make the draught of living dead and succeded in order to write down the correct instructions.

Therefore Snape would automatically be capable of producing the draught of living dead just as well as Harry, and possibly even better.

But as I said, this is just in the movies and my thoughts are only assumptions.

Neither took it in the book. I'm sure he used it in the movie to drive home the point that the Half Blood Prince's book was the ultimate potions guide, and whoever had used it before harry had earned the felix felicis by doing so.