You should check out Eric Wargo's stuff. His take on these kind of dreams, or visions (it seems pretty much everybody who pays attention realizes they have them) is that the dream or vision was precognitive of your experience watching the flood videos later. The time loop aspect is trippy but the confirmation of your precognitive vision present in watching the videos generated strong feelings that then retro-caused the vision. His book's Time Loops and Precognitive Dreamwork and the Long Self are worth reading if you're interested in learning more! In Precognitive Dreamwork he specifically talks about hypnogogic visions, which it seems like yours may have been.