Reason : your /tmp is noexec
The script need the /tmp to be exec please ask your system administrator to make it so.
As a temporary fix please do the following :
mkdir /usr/local/tmpdir
export TMP=/usr/local/tmpdir
You can now run the script without any errors.
After script execution is complete run the following
unset TMP
You should be good.
NOTE : This error should be fixed as of version 2.0.1 of our FFmpeg Installer.