Multi language: https://ftp.mozilla.org/pub/firefox/releases/50.0b11/win32/
Download en-US win32: https://ftp.mozilla.org/pub/firefox/releases/50.0b11/win32/en-US/Firefox Setup 50.0b11.exe
Multi language: https://ftp.mozilla.org/pub/firefox/releases/50.0b11/win64/
Download en-US win64: https://ftp.mozilla.org/pub/firefox/releases/50.0b11/win64/en-US/Firefox Setup 50.0b11.exe