I was flying on a commercial American Airlines flight from Tucson to Chicago. At around 5:30pm on December 1, 2014 the pilot announced we were passing over Kansas City. I wanted to try out the Time-Lapse function on my iPhone so I started videotaping out the window. While filming I saw a streak of light pass right below us crossing our path. I perceived it to be going extremely fast, much faster than we were going. My thought was a missile or a jet fighter. I kind of rule out a missile however because it seemed to keep a steady altitude. The two things that struck me were how close the object was in crossing our path and the extreme rate of speed. The pilot was kind of yammering about flight time (we were late taking off) but when the object crossed our path he seemed to stop talking mid-sentence.
I am including the video I took. Unfortunately because it is time lapse, there seems to only be three frames with the object. The entire clip is about 8 seconds although it was probably about a minute of actual time. The object begins in the bottom right of the video at about the two second mark. If you advance the video frame by frame it appears from the middle-to-right of the bottom of the frame and exits the middle of the right side of the frame. The first appearance is the best, the next frame it appears along with the city lights, and then the third frame it appears less intense.
I did overhear another passenger attempt to describe it to one of the stewardesses.