Minimoni Hinamatsuri! (ミニモニ。ひなまつり！)
The first video from Minimoni’s fourth single, released in 2002. I went looking for a copy of this on YouTube today but they all seemed to be dubs, live versions, other video variants, or had been taken down.
To own this and almost all their other videos, look for a copy of Minimoni Single V Clips 1 (ミニモニ。シングルVクリップ①).