Happy Fourth of July? Not for free agent NFL quarterback Colin Kaepernick.

In a Twitter message Saturday, the former San Francisco 49ers player denounced the nation's 244th birthday as a “celebration of white supremacy.”

Along with a video showing images of the Ku Klux Klan, police brutality, slavery and lynchings, Kaepernick wrote: “Black ppl have been dehumanized, brutalized, criminalized + terrorized by America for centuries, & are expected to join your commemoration of ‘independence’, while you enslaved our ancestors. We reject your celebration of white supremacy & look forward to liberation for all.”

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The video's disturbing images were over a backdrop of fireworks and actor James Earl Jones reading 19th-century abolitionist Frederick Douglass’ 1852 speech, "What to the Slave is the Fourth of July?"

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Kaepernick, 32, started kneeling for the national anthem before NFL games in 2016 to protest racial inequality and police brutality and has been a free agent since his 49ers contract expired in 2017.

No teams have signed him since, raising allegations that the league was deliberately blackballing him. But last month, NFL Commissioner Roger Goodell said he was encouraging teams to consider signing Kaepernick.

"I welcome that," Goodell said.

As Black Lives Matter protests continue across the U.S. following the May 25 death of George Floyd, a black man who died in police custody at the hands of a white police officer in Minneapolis, the country has restarted a deeper conversation about race, equality and American history.

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Kaepernick tweeted the same video on Independence Day last year.