Square or diamond shaped object hovering and moving very fast over Rochester, NY. 12/23/15 7:30 p.m. ETI was walking into an apartment building and noticed a very bright green light sitting still in the sky at what appeared to be maybe 7 to 10 thousand feet high. Just based on the brightness of the light and the fact that it was sitting stationary in the sky, I immediately pulled out my phone and started filming. I then watched for the next 12 or 13 minutes as this thing blew my mind. It appeared to be square, or diamond in shape. It changed from green to red then back to green in no real pattern. It did not make a sound. It traveled from one side of the city to the entire other in under 10 seconds. It dropped so low that it was out of my sight for a few minutes, then rose as if someone had a string attached to it and yanked it upward. I would say 1,000 feet to 10,000 feet in under 3 seconds. As it got close enough to me to really make it out I could tell the body of it was black, there were four huge perfect circle lights on the bottom, two red and two green, but at times there would be either no green or no red. I also saw a flashing white or maybe even amber colored light on the back? Maybe front? I am basing the size on a passenger jet which flew through the same vicinity as the craft moments after it disappeared which I also caught on video and I would say that it was half to 3/4 the size of the airplane which was a full size jet plane. It also appeared to be traveling 15 to 20 times faster than that plane which was descending to land and much much higher. This happened in Rochester NY and I witnessed it from the suburb Greece, NY. It was mostly south of my location, but at times traveled far enough north east (in under 10 seconds mind you) that I had to turn my whole body and face Irondequoit, NY, which is east of Greece, to keep recording it. I stopped a passing car and asked the young lady to look up and tell me what she sees so I know i'm not going crazy and she watched it for about 5 seconds, said oh my God that's a ufo! I said thank u for confirming and she promptly pulled away as if she was nervous. The craft made a lot of erratic movements. Stopping on a dime, zig zag patterns at times, shifting as if on an axis. At one point it started heading right at me and had me nervous enough to start walking back towards the apartment building for safety. It was acting as if it were investigating or searching for something. Truly a life altering experience for me, felt absolutely nothing like a drone which is the infamous explanation i'm getting for this. I own a drone. I know what they can do. I know there's a wide variety of shapes, sizes, and uses for them. This was not that. Oh and I don't know if this relevant or not but I experienced a really bad headache about an hour after the event which would not go away to the point that I had to take tylenol for it. I NEVER EVER have headaches that lead me to have to medicate. Cannot remember one time in life. I don't know if it was just from all the excitement or what.