Strange sighting in Denver 11/24

I searched local news reports and some other resources and no one else has reported what I saw. I did not have time to get a picture due to having a piece of junk cell that takes like 5 minutes to load up the camera but I really just want an opinion from the community.

It was midday, blue sky. The location is the southern part of Denver, a little bit west of where I normally see flightpaths go outside of DIA. From over the treeline I see a steadily moving, asymmetrical, black object moving at a constant rate of speed. It seemed to be significantly lower than a normal flight and it looked like it was drifting. It went at a very high rate of speed and was out of the range of my vision within about 45 seconds.

Now I am not saying that this is what in fact it is, far from it actually, but all I can think of to describe something similar are the grainy videos I have seen about "flying" people in Mexico City. Here is a youtube link

I don't want to embed because I honestly don't think that is what I saw, but the motion and seeming purpose of it was similar. I personally think that it was some sort of craft of unknown origin. It appeared to move intelligently at a fast rate of speed on a windless day. Please give me your thoughts and maybe some links to similar sightings.

Once again... I do not think this was a flying psycho mexican witch like in the video, that's just what the motion reminded me of.

Playing skeptic's advocate, even though it may be 'windless' on the ground level there very well may be a breeze up higher. With that said, it sounds like a black empty trash bag may be your culprit. And for the record, I've seen an other worldly ship up close and pretty personal... There's no mistaking it!

Look up "Williams Aerial Space Platform."

That's exactly what the Mexican "witches" look like.