That part of Wiki is out-of-date. (The same can be said about the Shorten format itself.
)
There is a Shorten plugin in the skins & plugins download area, but the last version that worked with it was MC11.1.
I have downloaded a few live shows in Shorten format from archive.org, but I always convert them to some other modern lossless format.
You can find some info about Shorten tools at etree.org. A Google search can also find info about conversion tools.
