Amazon is adding some serious star power to Prime Day -- and it's streaming Thursday! To kick off the sales event — which runs June 21 — 22 — the online retailer announced the Prime Day Show, a three-episode musical special releasing free on June 17, featuring Billie Eilish, H.E.R. and Kid Cudi.«These iconic artists have not only broken new ground in music but are inspired storytellers, culture creators, and visionaries,» Jennifer Salke, Head of Amazon Studios, said in a statement to ET.