I think that "omitting contrary views" as people often describe "echo chambers" or "epistemic bubbles" (mentioned around 3:30 in the video), this "omission" is really only half of the problem. In fact, within any ideologically slanted discussion group, there is often plenty of discussion of opposing views. It is very common for people in a pro-skub forum to post what they claim are examples of anti-skub thinking.
The problem is, the pro-skub forum will end up focusing on and overanalyzing the most extreme, poorly argued, misinformed and generally ridiculous versions of anti-skub viewpoints. Supposed smoking guns that prove the depravity of the anti-skub faction will be screenshotted, stickied, and memed to death on the pro-skub forum. This results from the simple desire to entertain others and fit in by finding examples of the enemy behaving badly, so the more enterprising pro-skub users will hate-read anti-skub forums looking for the worst things they can find to use as ragebait.
The anti-skub forum and its members, meanwhile, are doing the exact same thing in reverse. The result is that people do "engage", and quite frequently, with the opposing viewpoint, but only with the stupidest version of that viewpoint. This does not lead to understanding.
Also, here's a YouTuber who made a long video talking about how videos are too long. Best watched at 2x speed.