A SeaWorld official sent the video to reporters as former trainer John Hargrove was beginning a tour promoting his book "Beneath The Surface," which alleges maltreatment of orcas.
Hargrove was an orca trainer for 12 years at SeaWorld parks in San Diego and San Antonio.
Since leaving SeaWorld, he has become one of its harshest critics. He was featured in the documentary "Blackfish" and testified in support of a bill in Sacramento that would have forced SeaWorld San Diego to halt its killer whale shows.
SeaWorld's corporate office in Orlando sent an email to reporters this week, restating its allegations that Hargrove has "repeatedly provided statements that are misleading, false or in conflict with statements he has made previously."
A link to the video that SeaWorld said it had received days ago "from an internal whistleblower" was included. The video "is particularly reprehensible since John Hargrove is wearing a SeaWorld shirt."
The unedited video, in which the racial epithet was used, was posted to YouTube.
After the video became public, a La Jolla bookstore canceled Hargrove's book-signing, which had been set for Wednesday.
In an interview Wednesday with KPBS in San Diego, Hargrove said the N-word is "offensive language" and should "never be used."
The video was taken five years ago, he said. "The night that that happened, I hardly recall any of the events."
After seeing the video, "I cringed when I would hear myself say those things," he said, adding that in his drunken state, he thought he was being funny.
Still, he said the video does not undercut his statements about the maltreatment of orcas. The release by SeaWorld, he said, "is just an attempt to smear me."
Among the things SeaWorld accuses Hargrove of misstating is the assertion that trainers sometimes deprive killer whales of food.