Download .mp3 instead of playing them in firefox for android? Firefox on android auto-plays .mp3 links as you click them. How do I download them instead of immediately playing?
In the Firefox address bar, enter about:config.
Search for media.play-stand-alone.
You can see true below the item's name.
Tap the item's name (not on the search bar). 
A Toggle option has appeared at the bottom right. Tap it once. Notice the true has changed to false
Now, when you'll tap on a .mp3 link, Firefox will prompt you with a Complete action using dialogue. To download the file, choose Download.