What is "widevine media transformer" plugin?

every time i try to watch starz movies through my dish online account, it tells me i need to download this plugin, now i realize that both dish and starz are professional companies, and there is little chance that this is some malware and spyware laden download, but i try to make a point of knowing what the heck things are before i download them. so does anyone know what this is or what it does, or if it should be trusted?