Amid goofy cat videos, makeup tutorials and other assorted detritus, YouTube is swarming with unknown singer-songwriters just waiting to be discovered. New Orleans resident Samantha “Princess Shaw” Montgomery is one of the thousands participating in this low-odds lottery. When she’s not working as a caregiver in a nursing home, Princess uploads stunning original a capella songs and vulnerable video diaries. No one seems to take notice; her videos never garner more than a few dozen views. But what if one of those anonymous souls could somehow make a difference? Uplifting and clear-sighted, the ingeniously conceived Presenting Princess Shaw is a bracing look at a massive talent waiting to be unleashed if only the world would stop and give her a chance. (CB)Preceded by a provocation from Dr. Mehret Mandefro.