She did NOT sing MY ALL...she sang Red Line. Lee-chan just misremembered.
Ayu said that at each tour location, a different dancer would teach the audience the dance, so this time it was Shuya, and yes...everyone called him Avatar. The rest of the MC was spent introducing the six performers [Ayu refers to them as 'performers' rather than dancers', and in keeping with that, before she does her last little run up the catwalk she shouted for us to applaud "saikou no bando, saikou no dancers, saikou no performers, saikou no staff~" (band, dancers, performers, staff.]
And when we were at Shin-Yokohama we met the performers (the three clowns, and then two of the three dancers who do the stunts with the glow in the dark rope during About You.) It was me who spotted them, ehehehe.
