The Strain TV series is an upcoming vampire TV series by renowned director Guillermo Del Toro, and its viral marketing campaign is slowly infecting the far reaches of the Internet. A viral commercial (filmed as an amateur camcorder recording a la Blair Witch) was released on YouTube and sets the stage for what will most definitely be a very eerie series.
The video depicts a couple at a restaurant as they bear witness to hordes of rats scampering to the sewers in alarming numbers, hinting at something worse coming. That something is the show's premise, a global pandemic illness with vampirism as the main symptom. This viral campaign will definitely pique the curiosity of viewers, and get them interested in seeing more, if only to put these strange clips into context.
Additional pictures from http://collider.com/tag/the-strain and http://popwatch.ew.com/2012/09/21/guillermo-del-toro-fx-the-strain/