The numerical IP
are mediafire.com.
The numerical IP are used for the actual download link.
For me, the numerical IP does not appear until
after I have already clicked the download link.
All downloads have worked for me even with nothing allowed.
With mediafire.com alone allowed, all downloads still worked.
I typically Alt+click to start my downloads.
(Appears that is why I haven't noticed any problems on my end.)
With nothing allowed, simply left clicking, it appears you must do it twice?
If you have Allowed mediafire.com, it looks like you also have to click the link twice. The "Try again" appears, you click that, then the Download link shows again, then left-clicking that & the download starts.
Suppose it's some screwy way in which they're "firing" the links.
Alt+clicking or FlashGot Link the link, as opposed to left-clicking, circumvents the issue.
Just some other URLs for testing purposes (as one you've click, clicked, a subsequent open will not require a clicking twice):
http://www.mediafire.com/?9lsbz4sm83t8j3b
http://www.mediafire.com/?4len75ugez23cln
http://www.mediafire.com/?3p791mcosd294xf
http://www.mediafire.com/?ln71ze21lil0p0w
http://www.mediafire.com/?ryhxsymrr83zs7r
http://www.mediafire.com/?nq44tzgpzi1mi0i
http://www.mediafire.com/?1ppbeobaq8k7oba
http://www.mediafire.com/?337i4vqn03qxq6m