McAfee is surely wrong: since many people use Mediafire to exchange pirate stuff, McAfee might have just decided to ban the whole site.
Mediafire is a perfectly legit high bandwidth host like many other out there, and we have a full business account with them, so it just doesn't make much sense for McAfee to ban the whole site, just because it *might* be used for piracy. We need a specialized high-bandwidth host, because we have a Trial version so, we probably consume 10x the bandwith of another Flightsim developer that allows to download only after purchasing, and/or for a limited time.
I hope your antivirus/firewall will at least give you the ability to whitelist a site (but note that, Mediafire has each download on a different server so, you might have to whitelist them all), and the antivirus doesn't complain about the executables as well, something that McAfee is known to do for no reason, which is why Flight1 also suggest not to use it for Flightsim, since it wrongly flag their own products modules as dangerous as well.
We use Microsoft Security Essentials, which is tightly integrated with Windows, is always updated without being tied to a subscription, doesn't take too many system resources, is very simple to use, it has the important ability to let the user to exclude specific files/folders from scanning and never mistakenly identitfied our modules as dangerous. And, of course, is entirely free.