Phone downloads mysterious file
Possibly a flash animation file. Without access to my computer, I can't find out for certain.

As for why it showed up in your downloads? Most likely an error in a program that caused a download notification when downloading cache data or a temporary file, judging by the filename. Probably an advert or small animation from a webpage or app. 
It's worth noting that most free apps have ads as well as most websites, and most advert animations are flash animations. 

TL;DR: Probably a glitch causing an advert or cached page animation to appear in your downloads.