The one that converts flash to html5. I forget the name.
Oh yeah. I had to disable YouTube Center because it turns out Safari now changes YouTube into HTML5 automatically. Unfortunately you lose other features the extension enabled but at least it's fucking HTML5 without an extension. If only it could also automatically disable auto-play and convert all other videos somehow and disable autoplay there too it'd be fucking amazing. This is why I use Safari now.
Plus it means less extensions to enable. I only have a handful anymore:
1Password because it's indispensable
QuickStyle because I need something to zoom the text on a lot of websites (GAF included) because at 1200p everything is fucking small and Safari doesn't remember your Zoom setting
Occasionally I also have NinjaKit enabled which is a GreaseMonkey extension so I can use YouTube Me! on GAF. I do wish YTM had some options to disable certain features though. The YouTube part and Vimeo parts work great but Safari will not support embedded .webms no matter what. You have to click them. Also, even though SoundCloud works, it usually reports an error anyway. I'll probably just modify it to ignore .webms. I do wish I could get it to embed them properly in Safari. Weird thing is they play in Safari if I click. They use QuickTime plugin. But they won't show when embedded in a page. Maybe the code can be changed a bit to force it? I dunno. I should go hang out in the official YTM! thread and talk to hate radio about it.
Ultimate Statusbar because come on! Every other fucking browser has that disappearing status bar that only appears when you hover. But Safari still fucking uses a "status bar" that a lot of browsers don't even use anymore. Even most Firefox extensions ignore it anymore. No one wants a full status bar. Can Safari extensions even put anything down there? It's like it's just for the URL. So why not just make it like Chrome, Firefox, Opera and even IE now do? Come on, Apple. Even if you put the URL in the addressbar when I hover. As long as it shows up somewhere. I hate not knowing where a URL will take me. This is pretty much the only extension I would really get rid of if I could aside from NinjaKit if I didn't like embedded YouTube so much. (Why hasn't this been built-into GAF by now? At least maybe special tags for YouTube and Vimeo and the others.)
AdBlock for obvious reasons. Obligatory "Disabled on NeoGAF of course" post.
And lastly, BetterTTV because Twich fucking sucks and the dark theme is super useful as are the other features it gives.