Primer, written and directed by and starring Shane Carruth, is the polar opposite of Safety Not Guaranteed, the last movie I watched about time travel. While Safety Not Guaranteed is a light and funny romantic comedy that mostly uses time travel as a macguffin, Primer is a slow and intense meditation on the mechanics and dangers of time travel. Both movies are terrific in very different ways. Primer isn't a found footage film, but it feels real.
You can rent it for $3 at Amazon. Or you could buy the DRM free version with limited edition poster at Carruth's site.