Federal prosecutors say 38-year-old Norman LeBoon pleaded guilty in Philadelphia on Tuesday to two threat-related charges.
They say LeBoon called the congressman "a liar" and "a Lucifer" in the video and vowed to shoot him.
Authorities are not linking the March video to the bullet fired through Cantor's campaign office in Richmond this spring. Police believe that was a random act.
After LeBoon's arrest in March, prosecutors said he suffers from multiple personalities.
Neither they nor his public defender immediately returned calls for comment Tuesday.
LeBoon faces up to 15 years in prison at his Feb. 3 sentencing.