yeah. it's confusing but it's important to realize "short volume" is not necessarily (and most times it isn't) people shorting the stock.
if you don't have a position and you buy that's long volume if you don't have a position and you sell, that's short volume if you're long, and you sell that's short volume as well if you're short, and you buy to close, that's also long volume.
so short volume isn't actually people shorting, it's people (taking the initiative to) selling, which is a different thing altogether. it doesn't give any indication to how many people are actually short.
if you browse through that file for every ticker you'll notice short/long volume is pretty much 50/50 most of the time, which obviously makes sense.