"She is literally reading from something behind the camera," one fan commented on the video. The comment attracted more than 7500 likes.
"It looks like she is reading what she has to say," another fan wrote.
"Brit, you in danger girl," one woman wrote.
"She is reading everything because she is being manipulated to say these things," another fan wrote.
"The fact that it's phrased 'heard' says she doesn't have access or control," another fan wrote.
"She said I heard you've been writing in! This is a slip-up and a sign that she's not running this account," another fan wrote. "We love you girl!"
Fans have been voicing their concern about the pop star's welfare after she announced she'd take a break from work in January 2019.
Since that time, Spears' unusual Instagram posts have come under increasing scrutiny from fans, who often suggest she's not in control of the account.
Last week Spears made headlines after posting a video of herself dancing, tagging her ex-boyfriend Justin Timberlake.
Spears and Timberlake broke up in 2002, and he has been married since 2012. Spears herself has been in a relationship with Sam Ashgari since 2016.
Fans bombarded the comments of the video asking why Spears had tagged her ex. One fan suggested the star had "no idea this is being filmed … or broadcast on the internet".
Spears' father, Jamie Spears, is currently locked in a legal battle with his daughter over her $US60 million personal fortune.
Jamie, 68, has been acting as Spears' conservator since her public breakdown in 2008. Spears' lawyer Sam Ingham told the Los Angeles Superior Court last year Spears was "afraid" of her father and wouldn't perform until his conservatorship ended.
New hearing dates are set for this month, and continuing in March and April.
