A screw slips away from your grip and gets stuck
somewhere inside the player. You curse, and you start shaking the DVD player, turning it this way and that. You hear the screw rattling about, and eventually, after a few frustrating minutes, the errant screw falls out onto the floor (...at which point your cat bats it under the sofa. ;) )
You don't have any idea what tortuous path through the innards of your DVD player that screw took, just that it eventually (to your relief) fell out. Is it useful to speculate that The Hand of God was required to free the screw? That the screw at some point teleported from place to place within the DVD player? Why speculate about any of that (which, in terms of Occam's Razor "needlessly multiplies entities) when random motion over time is more than sufficient to explain the eventually extraction of the lost screw?
By analogy, the game played by mystics in a situation like this goes something like this: (1) Play the "you can't prove it wasn't the Hand of God" card, (2) imply that any lack of 100% absolute certainly suddenly puts all explanations on equal footing (with the mundane explanation being, in fact, for some strange reason, the least among equals), (3) saddle any rationalists with the burden of explaining and experimentally proving every single detail of the unseen path by which the screw traveled.
Why might you have a lingering feeling that some movie you watched was "important"? Why not? Our brains and the psychological processes going on inside them are pretty complex and only dimly understood. Why shouldn't the "loose screws" of the experience of watching a movie sometimes "shake around" inside those complicated pathways of processing inside your brain until one or two eventually "fall out" into a part of your brain which triggers the sensation "I know there's something important here!"? Maybe somewhere during the movie you saw a dry cleaning store in the background of a scene, and it triggered a not-yet-fully-conscious realization that you forgot to pick up your dry cleaning.
Where's the pressing need to "multiply entities" here, by dragging in new mystical entities, when the mundane components of such a situation appear more than sufficient for producing the observed effect?
and as you said, you do the best you can, and for many, that means a spiritual practice
Huh? You need a "spiritual practice" to deal with mysterious feelings about the importance of certain movies!?
A chicken is probably happier believing that the purpose of a chicken farmer is to house and feed the chicken. If the chicken had to go through life knowing the true facts of the situation -- that the purpose of the chicken farmer is to slaughter chickens for food -- her life would be a whole lot more stressful, filled every day with dread.
That a "spiritual practice" gives you peace, comfort, a sense of direction, helps you "do the best you can" to muddle through from day to day, etc., has little or no bearing on whether or not that practice helps provide "knowledge" in any meaningful sense. The accrued side-effect benefits of believing a thing are a an incredibly poor metric of the belief system's value as a path to "truth".