It seems like they're doing something similar to how Reddit's "hot" algorithm reportedly works. As of 2015, that was supposedly like:

log(upVotes - downVotes) - (hoursOld / 12.5),

according to https://medium.com/hacking-and-gonzo/how-reddit-ranking-algo....

Fair Trending basically differs just in the log() part, substituting (fractionUpVotes * views) for (upVotes - downVotes). This could change the ranking if a lot of people view without voting either way.