Monalisa Perez, 19, was booked into county jail after shooting at Pedro Ruiz as he held a book to his chest, believing it would stop the bullet.
The couple's three-year-old child and nearly 30 onlookers watched as she fired the fatal bullet into his chest.
Ruiz's aunt said they did it to increase their social media following.
Ms Perez, who is pregnant, is facing charges of second degree manslaughter.
The couple had started a YouTube channel in March, aiming to show the "the real life of a young couple who happen to be teen parents".
Last week Ms Perez told her viewers that it was a "blessing" to have her husband home for the forthcoming birth of their son, who is due in September.