It was a montage of scenes from the old X-Files show set to Sarah McLachlan's forlorn When She Loved Me.
"It was intensely romantic, and it almost brought tears to my eyes," Duchovny recalled.
"It really did. And it reminded me that we have at the core of The X-Files this very powerful relationship.
"We have to honour that and not shy away from the sentimentality of the fans or of the relationship itself.
"When we were doing the show, Gillian [Anderson] and I had got tired of it. And we wanted to be ourselves outside of it. I remember struggling.
"Now I think, `God, what a great love affair'."
Those are healing words for the intensely devoted fans of the television series that became a pop-culture phenomenon in the 1990s and made Duchovny's Fox Mulder and Anderson's Dana Scully a sort of Tracy and Hepburn, albeit with alien autopsies.
The show debuted in 1992, peaked with audiences in its fifth season but ran out of gas in 2002.
On July 31, the flashlights come out again, and FBI agents Mulder and Scully will restart their spooky romantic tango.
The plot of the film has been intensely guarded and Duchovny carefully sidestepped questions about the story cooked up by Carter and Spotnitz.
"You can ask, but my job is to not answer," said the lean 47-year-old who this year picked up a Golden Globe for his work in Californication.
Duchovny did confirm that I Want to Believe will be in the tradition of the "stand-alone" episodes of the old series, meaning it's not part of the long, complicated story arc concerning a shadow government and alien life.
A good portion of the movie was filmed in Whistler, the alpine skiing hub in Canada's Coast Mountains, and the intense snow on screen is majestic and unsettling as the agents chase their mystery.
"It's not a James Bond film," Duchovny said with a wry smile. "We're not chasing a guy on a snowboard. Not that that wouldn't have been cool."
The franchise hit the silver screen in 1998 with The X-Files: Fight the Future, and a sequel was expected in 2001 but legal quarrels between Carter and 20th Century Fox delayed the process, and then script and scheduling issues hampered the process further.
The film will acknowledge the time passage and even have a bit of fun with it, such as a scene early on in which Mulder and Scully, in a corridor at FBI headquarters, both glance purposely at the portrait of President Bush on the wall; the Clinton photographs from the 1990s are long gone.
"It's not like other science-fiction shows where time is frozen or you're in an unfamiliar world," he said.
"You've got to make these actual people who have aged and changed. For me, I thought I could kind of slip back into the character pretty easily, but early on in filming I found myself wondering whether I had done enough work.
"It was more of a challenge than I expected."
What helped?
"Working with Gillian again and that rhythm between us, that was probably the easiest thing and very helpful for me.
"I have seen the show over the past six years. Usually when I can't sleep and I turn on the TV and it's there.
"I do watch it for a few minutes and it's nice now. It's like home movies. But with autopsies." - By Geoff Boucher/ Los Angeles Times
