Following his graduation from Harvard, Barclay worked as a copywriter and creative supervisor at Grey, BBDO, Cunningham & Walsh, and Marsteller. Barclay then moved into music video directing and production through his own company, Black & White Television. He directed music videos for Bob Dylan ("It's Unbelievable"), the New Kids On The Block ("Games"), Janet Jackson and Luther Vandross ("The Best Things in Life Are Free"). Most notably, he created eight videos for LL Cool J, including "Mama Said Knock You Out", which won awards from both MTV and "Billboard"—and went on to be listed by The Rock and Roll Hall of Fame as one of the 500 songs that shaped rock and roll. In 2013, Complex Magazine ranked "Mama Said Knock You Out" as one of the top 50 rap videos of the 1990s, crediting it with creating "one of the most crucial links in establishing the cultural bridge between boxing and rap." Barclay was often hired to direct videos for films, introducing audiences to "House Party" (1990), "White Men Can't Jump" (1992), "Mo' Money" (1992), "Posse (1993)", and "Cool Runnings" (1993), among others.