This is a toggle for Safari download for SBSettings. It requires both SBSettings 2.99 or newer and the Safari download plugin for safari to be installed. Installing from Cydia will make sure both are installed automatically. The Safari Download plugin to Safari will allow some content in Safari that is normally only able to be viewed to instead be downloaded. Note that using this toggle will kill safari. This is the only way to have the changes take effect currently.
WARNING READ THIS: If you have bossprefs and Safari toggle installed, make sure you *enable* the toggle in BossPrefs then respring or SBSettings will not see that you have Safari download plugin installed and no toggle will show up!