°C-ute have uploaded the MV to Arigatou ~Mugen no Yell~ to their official Youtube channel.
Arigatou ~Mugen no Yell~ / Arashi wo Okosunda Exciting Fight!, will release on October 28 in six editions: two regulars and four limiteds.
The limited editions come with a bonus DVD and an event lottery ticket. The regular editions come with a random photocard. The CD covers were released earlier.
Purchase through CDJapan