Being a democrat I see a lot of left wing videos and links on my twitter and Facebook, unless of course my Republican friends share or post something political. Facebook also always has ads for a clothing website I sometimes shop on, I noticed the website wasn't heavily promoted on my feed until I had already looked at it on my own. My Pinterest is full of pins related to things I search and save, not differing too much outside what I already look at.
I think filter bubbling is a smart idea for social media to use because it makes users happy to see what they like, if they were to see a lot of things they didn't like they probably wouldn't be using that form of social media. But on the other hand I find it kind of disturbing that the internet tracks and promotes your interests so heavily. Nothing is kept a secret. How are we supposed to branch out and find new things?