When you are saying you have a movie, it’s easy to say that you have a riffed version (“I have the MST3K/CT/FC/Rifftrax version!”), but what do you call a movie that HASN’T been riffed (or the non-riffed version).
Non-riffed sounds too tame, and “straight” doesn’t seem right either (esp. for a comedy [possibly only intended] movie.)
I just say I watched the un-riffed version. I’m not worried about it sounding tame, as long the point gets across.
The Virgin Version.
Vanilla versus spicy.
The un-riffed version, maybe the original version.
Or possibly no qualifier. The riffed version gets the qualifier.
Another vote for “vanilla”.
That’s, like, the square version, man.
I just say “Movie.” 
I like to keep things simple.
The Snyder Cut
How did I know you’d get there first?!
Because I love food?
The painful version.
The Marvin.
As in, “I saw the Munchie Marvin. It was rad, dude”.
Back in the days of webrings, people who did MiSTings (basically doing MST3K style typed riffing of fanfics) called non-riffed stories “Bot Fodder”…so maybe that?
Personally, I’d call it “meh.”
I would also like to submit “Without a net.” As in, “I just watched Hobgoblins without a net!”
With some of these movies, it probably is that dangerous to watch them unriffed. 
A blank canvas
Potential future Mystery Science Theater 3000 episode…
Every now and then I get to flex my Linguistics degree and talk about marked and unmarked classes. That’s what Vader is talking about here, and I stand behind this 100%.
Unless you’ve got a really funny name for the concept, then I’ll declare my studies a waste of time and money.