Yup, self-explanatory, right?
Nevertheless, the whole Facebook experience, which has been, so far, enough of an adventure, escalated to a whole new level of stupidity, with the "video autoplay" feature.
Technically speaking, the "autoplay" feature, freshly implemented in Facebook, chips your bandwidth to the point that, sooner or later (rather sooner), your Facebook page will be as dead as a doornail. In layman's terms, the "autoplay" thingie is like a lap dance: you will enjoy it until your pockets are empty.
Without further ado:
In Firefox: Click on the arrow that points downward (near the padlock icon). From the menu, select Settings. On the left hand side of the screen, select Videos and switch the autoplay option to Off. That's it.
In Chrome: probably the same procedure, except this time you'll have to fiddle with the extensions and plugins, too.
In Internet Explorer: Don't know, don't care, hehe.