Finally got it to work. Didn't realize it had to be on a hosted server.<clip>
bind 9 "ulx urlplaysound h1tp://bit.ly/1BjN6Mr]http://bit.ly/1BjN6Mr" and different variations seem to not work
Not sure why you didn't know it had to be hosted.
put the url in quotes ulx playsound "your:URL" - though, yes, you may have trouble doing that in console if you don't know how to escape them out.
The original post and few conversations later in thread state that you have to link to a internet URL.
Also, the file link has to end in a supported file extension of .mp3, .ogg, .pls,
Whatever you're trying to use doesn't end in one of those. (Though, it does redirect, I'd guess that Gmod http.Fetch won't allow redirects, nothing the author can do to fix that)