"it went to her Cruel Intentions co-star Sarah Michelle Gellar"

TV This Observer interview with actress Selma Blair's a feast, especially this paragraph which is brimming with trivia for fans of the old WB programming of the 90s:

"We joke about how things could have been different if she had not suffered early rejections, such as not getting the lead in Buffy the Vampire Slayer [it went to her Cruel Intentions co-star Sarah Michelle Gellar] or Joey Potter in Dawson's Creek. "There was me, Katie Holmes and Marla Sokoloff up for it," Blair explains, "and Katie got it, which was absolutely right – she was perfection. But I could be living in a castle right now, with Tom Cruise as my husband." Would she like that? "I would, because I have such a crush on him! Not as big a crush as I have on Bill Nighy. But I wish someone would jump on a couch for me…"

Selma Blair as Buffy: The Vampire Slayer?  This was presumably while they were making the pilot episode with the wrong Willow.  That's, well, that's, well, I'm not quite sure what that is.