Four corporate drones trying to spinoff a cool startup accidentally discover time travel in Shane Carruth's dark SF flick Primer, a Sundance hit in 2004. Carruth's tale explores what happens when time travel doesn't work quite the way you'd expect — to travel back in time 6 hours, you have to sit in a cramped time machine for 6 hours getting bombarded with half-understood radiation and gasses. It makes your ears bleed and your handwriting get shaky. You may see yourself die, or you may actually have to kill one of your doubles. And yet the power of being able to change time is so addictive that our two main characters, Abe and Aaron, can't stop. They do nothing but go back in time again and again, living on crackers and bottled water in a storage space where they've stored the time machines. And then things really begin to unravel.
Abe and Aaron make money online by predicting the stock market, only to realize that if they cash out they'll raise red flags and probably get caught. Eventually, they find themselves doing nothing but trying to figure out temporal paradoxes, going slowly mad, as they try to prevent their own murders and prevent their other selves from figuring out what's going on. The dizzying cinematography and sharp writing enhance our sense of time gone blurry — conversations fade in and out, characters appear and disappear without warning, and events happen in reverse-order, only to happen again in a different way. You may want to start over at the beginning once you reach the end of the video, and you'll be rewarded if you do. Primer is about the dirty underside of time travel, the ugly truth of what it might really be like.