Article continues below advertisementBritney Spears' behavior has continued to spark worry over her mental health.On Monday, December 8, the pop star uploaded a video aboard a private boat where she showed off her figure in a hot pink string bikini. The racy clip featured Spears slightly pulling down on her swimsuit bottoms, pushing her cleavage out and untying her top.Article continues below advertisementBritney Spears Reveals She Injured HerselfSource: @britneyspears/instagramBritney Spears untied her bikini top in a new Instagram video.