I heard somewhere that whenever you click a thumbs-up or thumbs-down feedback anywhere online, that Facebook has access to that data.
Incidentally, this is why I haven't clicked thumbs-up on any of your posts.
It only applies to sites using facebook API. This forum doesn't use it, so facebook doesn't knows what you do here.
AndrewBurns There's no Facebook integration on this site. Nor on YouTube as far as I know.
However, if you ever see a Facebook "Like" or "Share" button (or a "Log in with Facebook" button) on a web page--then it's too late and Facebook already knows you've visited that site... and probably a whole lot more about what you did there.
If you're concerned about Facebook tracking you, might I suggest that you install the EFF's Privacy Badger browser extension. This will selectively block any trackers, including but not limited to Facebook & Google.
Or better still, don't use Facebook. 🙂