When I try to download something, it pops up an ad saying something like "Congratulations, you won $1,000,000! Click here to claim your prize!" or "Adobe Flash is out of date!" (when it's not). The only way to avoid this is to right-click on the download button and press "Save as". This is why I use MEGA or Google Drive or Dropbox. Never use Mediafire!
Nothing bad happens, it's just an old website made by Robert Rodriguez for his film studio.