A native of Greensburg, Pennsylvania, Vidmer played quarterback for Hempfield High School in the early 1960s. He was one of the finest prep quarterbacks ever produced in the State of Pennsylvania. He was recruited by many schools, including Ivy League schools, but enrolled at the University of Michigan.
As a freshman in 1964, Vidmer suffered a broken leg and torn ankle ligaments during a football practice session. Vidmer never recovered fully from the injury, recalling later, "I was never able to move around like I could before. It made a difference in my effectiveness. I was not as formidable a player as I once was." He started only three games in the 1965 season. In 1966, he was recovered sufficiently to be the starting quarterback in nine of Michigan's ten games. He also started four games at quarterback for the 1967 Wolverines. In his playing career at Michigan, Vidmer passed for 2,400 yards and 11 touchdowns. His career best game came against Minnesota in 1966 when Vidmer threw 15 completions for 210 yards and three touchdowns. He also threw for 258 yards in a 1966 victory over Oregon State. Vidmer was also an outstanding student at Michigan and was selected as an Academic All-American in 1966. He received three degrees from Michigan, a bachelor's degree in economics, a master's degree in international relations (1972), and a Ph.D. in philosophy (1978). He later taught at the University of Virginia and served as an advisor to U.S. Congressman Don Bailey, a former Michigan football teammate. He also served as a county commissioner in Westmoreland County, Pennsylvania. He was court-appointed to the county commissioner position in 1985 and elected to the position in November 1987. He became the chairman of the county commissioners. Vidmer was diagnosed with multiple sclerosis in 1983 and was forced to retire in 1999.