Zizek is quite a prolific writer, and so I hence hope you'll forgive me for linking to a book that I haven't myself read, but this book appears to be the one which is most geared towards the question at hand (especially given that it shares its name with Zizek's talk).
As I side note, I must admit that I do completely understand the frustration that comes with people constantly posting videos like this in an attempt to justify themselves, hence I can understand you posting what you did as a response to that.
either got too high to go...
Sounds like a lack of willpower to me.
Well, by the looks of it, almost the entirety of the talk.
Seriously though, are you kidding me? The author of the rebuttal criticises Slavoj principally for not offering alternatives and for not fleshing out his ideas fully. This animation is 10 minutes long. Do you seriously think that Slavoj went to give a talk at the RSA which lasted 10 minutes? Give the man a break. I highly doubt that in his talk, which featured questions from audience members and panelists, he did not address any of these questions at all.
If you want a more precise answer of what the author missed, then I doubt it would be possible to condense this to a 'smidgen'. This is not a small topic and I suggest that if either you or the author of the rebuttal want a decent idea of Zizek's ideas regarding society then reading his work would be a better start than watching a 10 minute animated clip.
I learnt that Cologne and Koln are the same city; beat that.
I think Slavoj Zizek pulls off the beard better than Eliezer.
The Zizek response is absurd. He criticises Zizek for not giving any alternatives to (cultural) capitalism, and yet he clearly has never been in the same room as a Zizek book. How can you expect to know everything that there is to a writer's thought by watching a ten minute video. Reading a chapter of HPMoR doesn't entitle me to sweeping opinions on Eliezer's philosophy.
Edit: Please explain how the Zizek video is "bad/incorrect/flawed/misleanding/incomplete".
I hope you enjoy it. Even if you dislike his arguments, his writing style is wonderfully unique.