That's pretty significant

I'm more and more struck by how movie!Snape is different from canon!Snape. In the movies, he's been less nasty to Harry (except that one added scene where he smacked Harry and Ron on the head), thrown himself in front of wolf!Lupin to protect the kids and it wasn't clear that it was he who outed Lupin at the end of year 3. And we were deprived of his Hospital Wing tantrum slightly before that (if you pause it when Harry & Hermione are going back in time, you can see Snape was there but he doesn't appear to be throwing a tantrum).

Now we have this review/summary of an early screening of OotP, and a couple of major changes have been made to the Snape's Worst Memory bit.

( movie spoilers )

It makes me wonder how different Snape seems to people who've only seen the movies and not read the books. Then again, those people probably don't think about it all that much anyway.