Spotted 他一定很爱你 listed in the ending credits as a "KTV song". Will post here if I find out anything more.
In the meantime, A-do will be appearing in two star-studded concerts in China, one in end March and the other in end April.
Secrets for Sale official site: http://entertainment.xin.msn.com/zh/tv/channel-u/programmes/secrets-for-sale.aspx