zendo data size restrictions
The system described in the quoted article depends on the security of AES with random keys (not only on the theoretical unbreakability of the OTP) for at least two things:


the encryption of large files, as apparent in the quotes of the question;
the initial establishment of the OTP, as shown by this other quote


  The first step is always optical, and that is an exchange of an AES 256bit key, plus an authentication key, and so those are the keys to encrypt the One-time pad as it’s being transferred wirelessly via Multipeer [or Wi-Fi Direct]… with a symmetrical AES key that was exchanged optically.



Claims that a practical system base its security directly on the OTP are typically misleading, on purpose as a marketing point or by incompetence, often both.



Addition per comment: the technique used for photos seems to be using 256 bits from the pad as an AES key enciphering the photo. This is not as secure as the OTP from an information-theoretic standpoint, yet this is believed practically secure when done properly.