A travel ban, however, remains in place on the freed defendants, including two women. Of the 29 initial suspects, five have gone on trial in absentia.
Abdulrahman Sabah Saud, the main suspect, renewed his confession at the second hearing that he transported the Saudi suicide bomber to the Kuwait City mosque attacked in June.
But Saud insisted he was told by the suicide bomber, Fahad al-Qaba'a, he would only blow up the mosque after it was emptied of worshippers.
Saud, a stateless Arab, said the footage was genuine and recognized the bomber in the video.
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The court set August 10 for the next hearing in the trial over the June 26 bombing that killed 26 people and wounded hundreds of others.
On Tuesday, Saud told the court he was a member of the Islamic State jihadist group that claimed responsibility for the attack, the worst in the history of the oil-rich Gulf state.
Saud also confessed to having transported the explosive belt from near the border with Saudi Arabia where two Saudi brothers, currently held in the kingdom, had left it.
Seven Kuwaitis, five Saudis, three Pakistanis, 13 stateless Arabs known as bidoon and another unnamed person at large were charged with involvement in the attack.
An IS-affiliated group calling itself Najd Province claimed the Kuwait City bombing as well as suicide attacks at two Shiite mosques in Saudi Arabia in May.