J. Cheney Mason confirmed that Anthony is the person featured in the video, the Orlando Sentinel reported. He said his client has been "maintaining notes for her personal use and for future counseling purposes."
Mason called the posting "unauthorized" and "inappropriate." He suggested her computer was hacked.
Anthony has been in seclusion since she was released from jail. A jury in July found her innocent of killing her 2-year-old daughter, Caylee.
The video is posted on a Web site, caseyanthonyisinnocent.com, and on YouTube. A woman who put it on YouTube said she assembled it from clips she found on Facebook.
In the video, Anthony talks about how she enjoys having a computer and camera. She does not mention the trial, her daughter or anyone else in her family.
"It's kind of nice, finally, to be able to say that I have some belongings that are mine that I will take with me after I leave here next year," she said.
The video shows a marked change in her appearance. Her long dark hair has been cut and is now blonde.