A group of five Democrats in the Senate have penned a letter to YouTube demanding that it remove instructional videos showing users how to build untraceable, unregistered firearms, which have been pejoratively labeled “ghost guns” by critics. The letter is signed by Sens. Ed Markey (D-Mass.), Richard Blumenthal (D-Conn.), Bob Menendez (D-N.J.), Chris Murphy (D-Conn.), and Cory Booker (D-N.J.) (pdf). Currently, YouTube’s terms of service prohibit users from uploading videos that show how to build firearms, ammunition, or accessories, but the five signatories say that those rules are not being enforced on the platform. “We write to express our serious concern that YouTube continues to host videos that instruct viewers on how to make and manufacture ghost guns. This content is a clear and direct violation of YouTube’s existing Community Guidelines on firearms,” the senators wrote to YouTube CEO Susan Wojcicki. “We are alarmed that an extensive amount of this dangerous …