On September 29, 1991, Nirvana's "Smells Like Teen Spirit" video premiered on MTV's "120 Minutes," an event that, in the years that followed, would come to signify the beginning of rock's great renaissance and usher in a cultural shift that would define a generation.

Of course, back then, it was just another video on another Sunday night, and no one — not even "120" host Dave Kendall — thought otherwise.

"I have to say, quite honestly, as soon as I heard that record and saw that video, I had no idea they were going to be as huge as they were," he laughed. "I was very, very impressed. I was moved but I really didn't have any idea it would explode to the extent it did. There's the truth."

To be fair, no one did. And so, in celebration of the 20th anniversary of the album "Teen Spirit" was meant to promote — Nevermind, of course — MTV News spoke with Kendall about the days before Nirvana became the biggest band in the world and about the alt-rock explosion that followed in their immediate wake. Needless to say, once "Teen Spirit" hit, everything changed and, as host of "120," he had a front-row seat for all of it.

"At that time, most of the music '120' was playing was quite separate from the rest of MTV. Some stuff had crossed over — like, we played Midnight Oil, we played Sinead O'Connor, we played Depeche Mode, the Cure — but a lot of our stuff was really closeted. It was still in this 'alternative' genre," he explained. "So the mood in the building at that point was 'Some alternative acts might cross over, the others wouldn't.' Like, if MTV had known that Nirvana was going to be as huge as they [were], they would've world-premiered the video in prime time, not late-night Sunday on '120 Minutes.' But then, I didn't know either!"

And how could he? After all, since creating "120 Minutes" in 1986 (and beginning hosting duties soon after), Kendall had been focused on trying to find bands he loved — "I was a bit stuck in my Anglo-centric, industrial, techno-pop mode," he laughed — and hadn't been paying attention to the storm that was brewing in the Pacific Northwest. So when the "Teen Spirit" video appeared at MTV, he'd never even heard of the band that would subsequently change the world.

"I hadn't heard Bleach, I wasn't that aware of new, American rock ... when I first heard the Nevermind record," he said. "I thought it was going to be another Seattle record, so I was a little suspicious and a little resistant to it because I thought it was going to be a lot of guitars, sort of a '70s feel. I didn't think it was going to be something new," he continued. "And then when I heard it, I knew I'd been wrong. It wasn't just heavy, it wasn't just rock, it was real melancholy, real passion, real vulnerability, the way it married intense rage with deep melancholy and sadness. And that really touched me."

Little did Kendall know that within a year the "Smells Like Teen Spirit" video would help bring "120 Minutes" to the mainstream and forever alter the show's playlist too. It's little wonder, then, that he'd leave the show the following year, though, with the benefit of 20 years' worth of hindsight, he can finally appreciate everything that happened following the premiere of that one little video. And, much like the rest of us, Kendall's still amazed by it all.

"It definitely changed the landscape of alternative music at that point. It had become slightly more guitar-heavy over the previous couple of years, partly because of the Seattle grunge influence, but that was the record that ushered in the 'grunge era' into the 'alternative mainstream,' " he said. "It brought guitars back into the music, and took the emphasis away from keyboards and synthesizers. It was gutsy and heavy and authentic, and that's what changed the landscape. Nirvana opened people's eyes."

Stick with MTV News as we reveal the Nevermind You Never Knew, celebrating the 20th anniversary of Nirvana's definitive album with classic footage, new interviews and much more.