[GoldAlchemist]

Spoiler for Some Other Interesting Stuff:

• At 4:30, after eating the beans, that following scene is very similar to one of Nagasumi-san in Seto no Hanayome.
• At 5:45, the manga Nagi's holding is exactly depicting the scenes just before it.
• At 6:40, that's Tsukuda Mina and Katou D of Getsumento Heiki Mina interviewing a baseball player.
• At 6:45, that's the Yakitate's scene.
• At 8:55, that's Tsukuda Mina and Katou D again, being chased by a crowd.
• At 9:03, that's mini Tsukishiro Mina flying.
• At 14:55, that Erina is probably from Kirarin Revolution.
• At 16:40, Himuro is performing and Taiga showering him with flower petals.
• At 16:43, Isumi's version of Match Girl.
• At 16:50, a Gundam model it is.

There're numerous Code Geass and Gurren Lagann references as mentioned in other posts. Sayonara Zetsubou Sensei's ones are pretty obvious too, including the one Nagi (acting on behalf Hata) to pay homage to Hata's own sensei. Between the ones that i wrote above and others have posted, there're still many other references that i don't know the names for sure but somehow saw them before.

Lastly i think Nagi is already free of the Geass power of Lelouch, as she mentions herself that she's already been manipulated by him once around 17:05 (Lelouch's Geass power can only be used once on a particular person).