This YouTube video discusses four subtypes of borderline personality disorder (BPD): a highly sensitive, internally focused subtype, a moody/theatrical subtype, an angry, externally focused, and impulsive subtype, and a depressed, internally focused subtype. Although these subtypes are not officially listed in the DSM, they reflect the variation in how BPD can manifest. The video highlights the important differences between the subtypes in terms of symptoms, functioning and treatment approaches. Finally, the prevalence of BPD is discussed, noting that it is difficult to determine.