Take a look at this post from @jmichaeltx in the thread you linked.
You're using the Folder trigger, which provides the path of the triggering file as %TriggerValue%, then you're redundantly looping through every file in the source folder. Instead, you should act on the %TriggerValue% directly, without a loop.
Edit: @tiffle beat me by a hair 
The solution was alluded to in that thread but never posted. Try this:
Move ALL files from Desktop to Downloads.kmmacros (1.7 KB)