"You don't have to Google it. I already did."
As for Blair, 48, she went on to say that the kiss "was a catalyst for so many young people to help them realise certain aspects of their sexuality."
Gellar, 43, added: "It also represented a paradigm shift to a new dynamic towards acceptance in pop culture. Also, it was super hot."
During the cheeky promo, the Buffy the Vampire Slayer actress wore an iconic 'KISS' band hoodie, whereas Blair opted for a sleek little black dress.
"I must say it was a really good kiss," Grammy nominee Blair said to her Instagram followers shortly after.
"My dear friend @sarahmgellar has been by my side through the excitement, the slow times, the changes, the kids, in sickness and in health. Thank you @rogerkumble for giving me this – my first big movie.
"And for giving me this space to say I have always been honoured to be an actress. To be allowed. To say thank you. It has been a dream come true. May we all kiss one day again soon. This one will always be a point of pride."
The special ceremony, which was postponed in June due to COVID-19, will be hosted by actor Vanessa Hudgens.
The show will feature performances and presenters such as Sia, Kevin Bacon, Neve Campbell, David Spade and Travis Barker.
Blair has been living an increasingly private life since being diagnosed with an aggressive form of multiple sclerosis.
The Cruel Intentions and Legally Blonde star was diagnosed with the degenerative disease in 2018 and appeared in public just months later walking with a cane and a walking bike.
Last August, Blair revealed her treatment left her immune system compromised, and she experienced hair loss. The actress posted the first picture to her Instagram account revealing the extent of her hair loss and her son cutting her remaining hair off.
In a 2019 cover story for People magazine, she opened up about her disease, saying she has experienced "constant weakness and fatigue" and spasmodic symptoms which compromise her control over her face and voice.
However, she told the magazine she had some things to celebrate including her followers on social media and the support of her family.
Last year, she also appeared on Good Morning America during a period of an "exacerbation" of MS – resulting in spasmodic dysphonia, a condition that alters her voice.
"I am very happy to be able to put out what being in the middle of an aggressive form of multiple sclerosis is like," Blair told interviewer Robin Roberts.
"It's interesting to put it out there, to be here to say, 'This is what my particular case looks like right now.'
"Let's meet again in a year and see if I'm better. If I'm not, and I can still have a conversation, that's good enough."
Blair admitted she was "a little scared" of sitting down for the interview given how the MS flare-up had affected her speech.
"My neurologist said, 'No, this will bring a lot of awareness, because nobody has the energy to talk when they're in a flare-up. But I do, because I love a camera!"
For years, Blair said she knew something wasn't right but didn't get the answers she needed until 2018.
"Ever since my son was born, I was in an MS flare-up and didn't know, and I was giving it everything to seem normal," she said.
"And I was self-medicating when he wasn't with me," she said. "I was drinking. I was in pain. I wasn't always drinking, but there were times when I couldn't take it."
Blair faced tiring days. She said simple tasks like driving her son to school would leave her fatigued, forcing her to pull over to nap before making it back home.
Her son, Arthur, who she shares with ex Jason Bleick, is now eight.
"I was ashamed and I was doing the best I could and I was a great mother, but it was killing me," she said.
"And so when I got the diagnosis, I cried some relief. Like, 'Oh, good, I'll be able to do something.'"
