In every corner of the world, at any given moment, random people post personal video clips online. They are their virtual messages in a bottle, tossed into the boundless sea that is the Internet. Most of these posts flounder in a sad limbo of indifference and anonymity-unless your YouTube handle happens to be Princess Shaw. Samantha Montgomery, 38, lives alone in one of New Orleans' toughest neighborhoods. By day she works as a caregiver for the elderly; at night she transforms into Princess Shaw, belting out soulful originals at sparsely attended open mic nights and posting homemade a cappella clips on YouTube, usually reaching just a handful of viewers. One of her followers happens to be Kutiman, a.k.a. Ophir Kutiel, an Israeli musician living on a kibbutz outside Tel Aviv, who mashes up YouTube videos from all over the world to create new musical pieces. Princess Shaw has no idea that he has found hers. A rousing documentary crowd-pleaser about a star-crossed singer-songwriter and ...