print(response_body[1]) возвращает:
[{"mid": 66, "name": "Nikita_Cerber", "body": "\u0414\u0430\u0440\u043e\u0432\u0430!!!"}, {"mid": 99, "name": "Oleg_Burmak", "body": "Broken eyes..."}]
print(table.concat(response_body)) возвращает:
[{"mid": 66, "name": "Nikita_Cerber", "body": "\u0414\u0430\u0440\u043e\u0432\u0430!!!"}, {"mid": 99, "name": "Oleg_Burmak", "body": "Broken eyes..."}]