According to the YouTube account of Mauricio Ruiz, the following footage was shot from the window of a SouthWest Airlines flight from La Guardia airport to Houston, Texas.
Ruiz goes on to say that he has submitted the video to FAA officials and is waiting further review from them.

The video shows an object outside the cabin of the airplane. The object does not appear to be a reflection of anything from inside. It does not look like a reflection of light on the window, especially not when the camera zooms in and we can see details on the supposed craft.

From Ruiz’s YouTube:
The actual footage in its original content was sent to the FAA for further review. UFOlogist and investigators please be patient. Let FAA do their review in fairness to all. Thanks.

What does it look like to you?