Firefox has started rolling out two-factor authentication, and if you use the browser to store any passwords you should enable it now.
Sometimes, you just don't feel like waiting for a video to stream. That, or a video is so compelling, you want to make an offline copy so you can pull it up (and show your friends) at a moment's notice.
If you're not familiar with two-factor authentication, it works essentially as a second line of defence for protecting your account. When you enter your password, you'll be prompted to also enter a numerical code that you'll get from an Authenticator app (some sites and services also allow you to get that number via SMS). That means that not only would a scammer have to acquire your password to get entry into your account, they'd need to have your phone as well.
Two-factor is rolling out now and should be available in the Settings menu of your Firefox browser soon. If you don't want to wait (you shouldn't) you can also enable it now by clicking this link and then tapping "Enable" beside the "Two-step authentication" menu item. When you do, a QR code will appear for you to scan to connect your account to an Authenticator app.