In December 2013, a calf of a Risso's dolphin escaped its enclosure at the Taiji Whale Museum, although it's whereabouts are unknown, they searched the entire perimeter for days and did not recover one beached dolphin anywhere.
In Russia, it's been confirmed at least one dolphin ("Dicky") was successfully released back into the Black Sea. Even O'Barry said "I have released lots of dolphins successfully, it's possible."
So why is SeaWorld still holding onto the myth that captive-born (or even veteran wild-caught dolphins) cannot be released back into the wild? We all know the answer. Let's hope the dolphins held captive in pens in Taiji are safe during the typhoon that is hitting that area right now. The Dolphin Project video reports from taiji showing swells and stressed out dolphins: in 2011 when there was another typhoon that hit Taiji, most the dolphins in those pens died, some were "lost." Two dolphins have died in the pens during the typhoon in Taiji. I hope that this time, the rest escape.