I came across this video on my Facebook newsfeed. As far as the main thrust of the guy's speech, I'd say that he's making a mountain out of a molehill. I don't believe that personalized ads or search results are even remotely dangerous.
One thing he talked about did pique my interest, though, and that was when he pointed out that Facebook started filtering out his conservative friends from his newsfeed simply because he clicked on his liberal friends' profiles more often. I've known that Facebook's been doing this for a while--I'm not certain exactly how long that's been, but it's never bothered me either.
However, it did make me think about why that is the case. Obviously, part of the reason is that Facebook's just trying to make it easier to find the things you're more interested in and filter out the things that you're less likely to be interested in. In my opinion, that's not necessarily a bad thing. What I do think is bad, though, is that we do this as humans. We did it before the internet ever came out, and I'm sure that we've done it for pretty much all of the history of our race.
I've noticed that as I came out of the closet and started posting more gay-related things on my wall, dozens of my old friends (and family) unfriended me, blocked me, or simply removed my items from ever appearing in their newsfeed. They don't like the things I'm posting (for whatever reason) and therefore, they avoid them. Interestingly enough, many of the people who have unfriended me have sent me an email explaining that they did so, and why they did so, and still considered me to be a good friend and a good person in real life, but simply didn't want to be reading my posts anymore.
I think this is very dangerous. This may very well be one of the things causing these filterings that this guy is talking about. People don't like to talk to someone who disagrees with them. People don't like confrontation (or, they do like confrontation, but only for the sake of fighting, not for the sake of actually holding an intellectual discussion). I know I'm guilty of this myself. I often avoid clicking on links that people post that are about things that I don't believe or agree with. I think it's very much a part of human nature.
We don't like to socialize with people that disagree. We view such people as enemies, contending against us on something that we believe. This is unfortunate, and dangerous. It causes people with a certain mindset to become more solidified in that mindset because they only want to socialize with people who have the same mindset.
For example, Mormons like to socialize with other Mormons. They home teach each other, they do activities together, talk at church, invite each other over for dinner. But, they don't branch out of that social circle as much as they should. I remember when I was at an activity with all Mormon people, we talked about this very thing. Many of them there were saying that they have very few or even no friends who were not Mormon that they regularly socialized with. Of course, they knew dozens and likely hundreds of people who were not Mormon, but they didn't go drinking with them, they didn't go to their parties, didn't invite them to their own parties, et cetera.
The same is true for liberals and conservatives. Liberals like socializing with other liberals and conservatives with conservatives. You tell a liberal that you're conservative and ey're liable to dislike you (or at least not choose to be around you during leisure time). People simply prefer the company of those they identify with. I mean, it's definitely true that you need something in common with someone in order to motivate having a friendship with them. But, to avoid any discussion with a person simply because they don't agree with you seems like a drastic overreaction.