We've got some pretty poor nighttime footage of a blue light that mysteriously appears out of nowhere, and then disappears again. I've asked for more details, but in the meantime, this is all we've got. The person who saw this and uploaded the YouTube video does not post UFO videos, though, so likely saw something striking in the sky and just wants to share the encounter. Did you see anything similar in McAllen recently? This is the third sighting in a pretty short time period to come out of South Texas (1, 2), a region that's not typically so active with such things.
Here's the video: