By default, we will try to download any URL you chuck at us! This will mostly work for simple URLs that point directly to a file we support.
(For example, something like this very nice Quake booklet: https://archive.org/download/quake-essays-sep-15-fin-4-graco-l-cl/QUAKE_essays_SEP15_FIN4_GRACoL_CL.pdf
will download without a fuss.)