"You're one year older, girl," Justin Timberlake (played by Nathan Keyes) says in the clip.
The upcoming two-hour film, called Britney Ever After, will span Spears' early days in Kentwood, Louisiana, her high-profile romance with Timberlake and her struggles following her parents' divorce, as well as her short-lived marriages to Jason Alexander and Kevin Federline. It will also cover Spears' custody battle over her young sons and career highlights like kissing Madonna at the 2003 MTV Video Music Awards.
Because the unauthorized project is moving forward without Spears' blessing, Bassett hopes that her hard work results in a performance that wins over the GRAMMY winner. (A rep told ET that Spears would not be contributing to the movie "in any way, shape or form.")
"I really hope she watches the movie, because I think she'd really enjoy it," Bassett told ET's Leanne Aguilera on the set. "It's really a love letter to her and to her story, so I really hope she watches it and I just wish her all the happiness in the world."