UFO Over Budapest

A UFO, looking like a classic "Flying Wing" saucer-shaped disc, was filmed during a rainstorm over the skies of Budapest, Hungary on Monday and posted to YouTube. What is it?

The description on the video claims the object was filmed during a birthday party and the sounds of revelers, speaking in a Slavic tongue, can be heard in the background. The sighting has an ominous look because of dark clouds and heavy rain pouring down from the sky.

The unidentified flying object moves slowly through the air with no flashing lights, very unusual for the weather. It looks like the classic V-shaped flying saucer but this time with a circular port in the bow of the craft.

The video includes a segment in which the object is enlarged but it doesn't help to identify it as any known aircraft, and it's definitely not a bird.

So, what is it?

Source: Gather.com