I would've thought download could just be unterladen (down-load) and downloads to be the same word with "den" prefixed or something like that, since it has "en" already, and can maybe work as plural and singular. My German isn't perfect, so don't take my word for it; I'm just giving off some thoughts of mine.
I usually use, for example: "Das ist ein Herunterladen." and people understand me just fine. Or, "Ich kann es herunterladen." if it's more of an action. Uhm, I think I'm with those that say you can just ambiguously say it.. in a sortof roundabout way. xD Hah. It's not perfect, at all, but it could work. Sorry to reiterate what you probably already know, but ho hum, there's my thoughts.
Ich fragte ein Deutscher Freund und er ist mal über das denken. xD Oke, leider er hat auch keine Ahnung, und so ziemlich sag dass du kannst einfach "download" sagen. -.- ...welche du schon gewusst. xD Mir leid!