I can't make out all the kanji on the sign in the last panel.
Anyone know what video this is referring to?

We talking about Haku, sadly Its most likely any video featuring her, Haku is the sexiest, but she cant sing.

Ralen said:
I can't make out all the kanji on the sign in the last panel.
Anyone know what video this is referring to?

Obviously it's referring to the infamous Tsumanne by Owata-P. It's forever associated with Haku, so whenever you see someone comment "tsumanne (boooring~)," especially in green text, it's referring to that video.

http://www.nicovideo.jp/watch/sm3447689

I just noticed the statue in the background of the last panel.

I was immediately reminded of this youtube video: http://www.youtube.com/watch?v=YersIyzsOpc#t=1m10s