Alright, so I watched the video so you guys don't have to. Here's a synopsis:

Youtube's ad blocking is going to backfire because:

• It caused people to stop using crappy ad blockers that didn't even work with youtube to switch to effective ones that do.
• Drawing attention to "good" browsers and ad blockers, increasing adoption -- including people that weren't using or aware of the existence of them in the first place
• Increased support of the people making/maintaining ad blockers. Spite driven increase in donations, subscriptions to paid ad blockers, bug reports, etc.
• Cites the Streisand effect.
• Analogy of how prohibition led to stronger drugs, stronger booze, etc. If you tell people they can't do something, they're more likely to do it and get better at doing it.
• Cites how Youtube's attempts to block ad blockers is breaking older embedded apps in smart TVs, chromecast, etc. Older or non-tech people are just more likely to stop using those rather than try to fix them -- and thus cut back on watching youtube.
• Believes Youtube's actions are an indication the internet's "free with ads" model is dying -- they're getting desperate to maintain profitability.