http://jp.youtube.com/watch?v=wTcLlsBz-bU
December 23 is a national holiday in Japan. It's the current Emperor's birthday and on that day he give a public speech from a balcony of the Imperial Palace. Normally the area is off-limits to the general public save for specially arranged tours.
Only on December 23 and January 2 can people enter the grounds of the Imperial Palace and listen to the Emperor give a public address.
This footage is from last year which pretty miserable weatherwise. The Emperor has cancelled his birthday address this year due to illness
ラベル：Emperor Akihito 皇居
待てば海路の日和あり
花を摘みとることはできても、春の訪れを止めることはできない