Just in time for the 40th anniversary of Ozzy Osbourne's debut solo album, Blizzard of Ozz, the Prince of Darkness has released a 30th anniversary retrospective of that period in Ozzy's career to YouTube.

The '30 Years After the Blizzard' doc is available to stream for free through September 25.

In it, Ozzy, Sharon Osbourne and various others close to the Osbournes — including Bill Ward, Zakk Wylde, Rob Halford and Lemmy Kilmister — discuss the importance of the Blizzard of Ozz album and especially of guitarist Randy Rhoads' invaluable contribution to heavy metal history.

A number of scenes in the 40-minute doc find Ozzy and engineer Kevin Churko combing through the multi-tracks from the album, with Ozzy reminiscing about the songwriting and marveling at Rhoads' maestro-like guitar playing.

Around the 12-minute mark, the doc cuts to guitar virtuoso Steve Vai (who was in Frank Zappa's band during Ozzy's Blizzard-era).

"When you listen to [Randy's] solos, there's actual moments of uniqueness," Vai says. "When I say unique, I mean, things that have never been done by a player."

The doc cuts back to Ozzy and Churko in a studio listening back to the end of "Revelation (Mother Earth)." Ozzy is talking about how the track was one of a few that took shape in the recording studio when he trails off, realizing that the track is continuing well beyond its ending on the album.

Ozzy and Churko lean in and Churko turns up the guitar track so an astonished Ozzy can listen as Rhoads improvises a stunning guitar solo for well over a minute.

"Wow," Ozzy mutters, with his mouth agape. "What's this?"

"It's just at the end of the take," Churko replies. "Randy just kept playing. He's just keeps going on (laughs). I'm not even [muting the other tracks], that's all that's on the tape there. So he must have just...had to burn off some steam or something. It's pretty cool though. I mean, I love it when I brought up these tracks and to hear those things that nobody's heard in 30 years."

"I've never heard that," Ozzy says.

Watch for the scene in the player above at around the 12-minute mark.

Photos: Getty Images

Earthday Birthday 27

EDBD 27 Tickets

GO HERE to purchase tickets.

About Earthday Birthday 27