User blog comment:G0LD3NF1RE/Skyrim Dawnguard DLC/@comment-3520040-20120507021439/@comment-69.146.244.153-20120507221050

He's referring to the actual Volhihar Vampires, the ones who can travel through ice. While there are those in-game that are name Volkihar Vampires, there are none that have that ability.