None. That's why the discussion is concentrating specifically on the video footage.I agree. These "pilots" might also, for example, be voice actors.
Excellent point! What data was used to rule out that the audio recording of the alleged "pilots" isn't fake?
On the other hand, I don't think we have any particular reason to suspect the audio is faked, but given the people involved in the TTSA enterprise and its "mission", it could very well be.