Oh I agree with you there and the guy in the video talks about this too. The algorithms are in place to make the product more appealing to people and thus more marketable. But as you point out the downside is that echo chambers are created as people are only getting fed the things that the algorithm predicts they are going to want to view.
And a consequence of this I believe people's outlooks are getting more extreme and less intolerant of other peoples views as the echo chamber effect takes hold and normalises a persons opinion no matter how outrageous it may be.
From veganism to zionism, right wing to left, and everything in between, these algorithms are bringing like minded people together, reinforcing each others views and thus normalising them.