acute urgency of bergdahl's health condition. >> indeed his health was growing more fragile. he'd lost a good bit of weight and we were very concerned that time was not something we could play with. >> reporter: but after the taliban released this video showing bergdahl walking to a u.s. helicopter, some said the health argument didn't make sense. so the administration went behind closed doors to show senators a so-called proof of life video shot by berg tadahlb taliban captors last december. some who saw the video said bergdahl did not appear ill. a physician told cnn in an exclusive interview something else. >> he'd been drugged with an antipsychotic or hypnotic drug. >> what makes you say that? >> you can tell, it was ease city. his speech was slurred. having trouble reading. had what's called listagmus. he'd been obviously drugged. >> you're not speaking as a senator. >> i'm speaking as a doctor. >> not possible he could have been beaten up? >> not at all. there's a total response...