I've never encountered the problem with Mediafire, but other people do report it from time to time. On my installation guide videos, I have backup links in case of that situation. Here they are:
Backup DropBox links in case Mediafire doesn't work for some reason
https://www.dropbox.com/s/qew6q975jamesve/DaiZy%2B_v%5BRz0%5D.rarhttps://www.dropbox.com/s/3zn95ugved0b5bk/DaiZy_v042c.Chernarus.pbo