this is what the uploader says

Date of sighting: September 2011
Location of sighting: Milpitas, California, USA

Note: Watch the light reflection off of this grey object. It changes as the cars position taking the video and the UFOs positions change. This is indication that the video is legit.

Although the location of the sighting is not mentioned by the poster of the video, I did notice the freeway sign at 57 seconds into the video that stated, "Calaveras Blvd, Milpitas 1 Mile." That gave me the city closest to the sighting and the UFO was headed in that direction. You can also see its a girl in a miniskirt taking the video, from noticing the reflection in the car window. Also note, the UFO did vanish when behind objects like telephone poles, trees and other objects, so I am very certain this is real.