Well I think we can safely say that this is NOT a UFO any longer thanks to the brilliant members here on ATS. I think the case can be closed on this
one.
The light seems shining from below the clouds.
Got this theory about a high voltage craft that burns up the nitrogen
in the air giving off a bright light.
Aas someone with over 10,000 flight hours in various aricraft, I can tell you that it looks very much like the sun reflecting off of the ocean. The
dimming at the end would be due to the sun possibly ducking behind some high altitude cloud layer.