Hello there!
You are right, I've got them too just now from Mediafire adds. This must be a recent problem since I've been using Mediafire services for many years without trouble.
I screen captured the malware notices and I'll contact Mediafire regarding this problem.
Please wait for a few days and try downloading again.
And thank you for letting us know about the problem.
edit: I just informed Mediafire about the malware problem. As soon as I get an answer I'll report it.