Okay, this was most likely a computer-generated hoax, but it's interesting to read all of the different reports and elaborations upon this subject. The eye-witnesses always make things even more hazy, but nonetheless, it was one of those daytime sightings that was worth a look.
Below, I'll provide a few excerpts from a couple websites along with a separate video link......
Summary: In September 1997, [Mexican TV host and UFO researcher] Jaime Maussan received a very special package. Someone had sent him a video tape, in itself nothing remarkable. But when he played the tape on his video recorder, it took his breath away. For the anonymously sent recording showed nothing but points of light and sky - except for a large, metallic, structured, rotating disk, which maneuvered in broad daylight over Mexico City, with a dateline of "Aug. 6 1997."
Enclosed with it was only a note, which read, "We know what happens to witnesses, if they go public with something like this." Maussan's first reaction was, "This is a fake; it can't be real!" Yet, on the advice of his colleague he viewed it carefully, again and again, and started wondering. In addition to the video, there were multiple eye-witnesses in the area.
You can read more, here:
To just view the full-sized video, go here: http://www.ufoevidence.org/videos/footage/MexicoCity1997.wmv
A couple skeptics conclusion, after studying the video for over one hundred hours:
"If the UFO were a real object "out there" beyond the building, this differential blur could occur only if the UFO suddenly moved with the random motion of the camera in such a way as to remain at the same location in the field of view of the camera even though the building image changed its position. That is, the UFO would have to track the motion of the camera. And this is in the time of one frame, 1/30 sec. Actually, in less than the time of one frame the UFO would have had to "jump" downwards many feet (I don't recall the exact number) and then back up again in the next frame because there is no differential image smear in the frame following.
As I recall there were two frames which show this very obvious differential smear. But Sainio studied all the frames and found that the building image smear was almost always greater than the UFO image smear. I should point out that Sainio and I spent well over a hundred hours analyzing that video. It was very interesting and 'looking good' until he discovered the differential smear. The differential smear (and also the image jump referred to by King) introduced an artifact that could not be explained unless one assumed that the UFO tracked the random hand vibration of the camera and moved in a rapid, jerky motion just enough to have its image remain unsmeared throughout the video. This seemed highly unlikely for the apparently smoothly moving (and rotating) object and so Sainio and I have considered this differential smear to be the 'fingerprints of a hoax'. Of course, we cannot explain the witness reports. We just wonder if there is really any connection."
[source = http://www.hyper.net/ufo/vs/m25-012.html ]
In my opinion, there was just too damn much wobble going on with that supposed UFO caught on video. Don't get me wrong, I definitely believe there is intelligent life on other planets and I also believe in "flying saucers" or at least some type of spacecraft that is not built by the struggling Homo sapiens. At any rate, unless the aliens in the craft depicted above were either drunk or having difficulty, I see no reason why it would hover in such an irregular manner. I would hope that an advanced race of beings would be able to zig & zag, hover, and dart off in a more uniform, smooth fashion. To me, that video looked like a classic replication of something you'd expect to see in a '60s Sci-Fi flick. Sort of shoddy, cheap & cheesy, but interesting...