Any questions about whether Nike might quickly back away from its decision to embrace the polarizing quarterback Colin Kaepernick amid threats of a boycott and criticism from President Trump dissipated on Wednesday when the company released a two-minute advertisement narrated by him and announced plans to have it run during the N.F.L.’s first telecast of the regular season.

The ad, called “Dream Crazy,” features Mr. Kaepernick and other star athletes in the Nike stable, including Serena Williams and LeBron James. It implores viewers to dream big, using the inspiring stories of those stars and of everyday weekend warriors who overcame illness or disability to triumph athletically.

“Believe in something, even if it means sacrificing everything,” Mr. Kaepernick says over images of him watching a waving American flag projected against a building. Those words appeared in an ad that was released on Monday announcing Nike’s new partnership with Mr. Kaepernick and on a billboard of him that went up in San Francisco on Tuesday.

“Nike’s ‘Dream Crazy’ campaign will air this week during sporting events such as the U.S. Open, M.L.B. and college football in addition to ‘Thursday Night Football,’ ” Josh Benedek, a Nike spokesman, said.