I don't recall anyone asking me, "What is a credible eyewitness of a living pterosaur?" When critics of our investigations never mention "Duane Hodgkinson," I suppose that could be a clue that Hodgkinson is a credible eyewitness. But seriously, how can we objectively evalute the credibility of an eyewitness? From my experiences as a forensic videographer and as a juror on a number of court cases, I would like to suggest some things that might help.
First consider two potential problems with witness portrayal of an experience: distortion from dishonesty and distortion from poor interpretation. Evidence for either one will cause us to give less importance to a testimony. I don't think of this evaluation process as an on-off switch; judge with some scale of gradation.
When words or behavior or manner of speech show a sign of dishonesty, we lose confidence in what was said. But some witnesses make a positive impression on those who carefully listen and observe. Many who have seen Duane Hodgkinson's Youtube interview are favorably impressed.
When conditions make a misinterpretation possible, we may lose confidence in the beliefs of the witness; we may believe that the witness misunderstood the experience. With Hodgkinson's experience, however, there is little room for misinterpretation. He and his army buddy, in 1944, in New Guinea, in the middle of the day, were in a small clearing when the creature, in that same clearing, took off and flew into the air. There was limited room for misinterpreting a tail "at least" ten or fifteen feet long. The wingspan was close to that of a Piper Tri-Pacer, or about twenty-nine feet. Hodgkinson was not drinking at the time, and has never been a drinker; nothing would have caused those two soldiers to experience the sight of a giant pterosaur at a close distance except one thing: a giant pterosaur at a close distance.
In the new second edition of my nonfiction cryptozoology book, "Live Pterosaurs in America," I delve into detail about cumulative evidence. Even when one eyewitness is not 100% credible, the addition of another eyewitness of a similar creature actually adds to higher credibility for the general idea that modern pterosaurs live on this planet, when both witnesses describe a similar living pterosaur. Thus we need not look for any procedure that will give us a very precise evaluation of the credibility of any one eyewitness; we need only look at the cumulative evidence: many eyewitnesses of modern living pterosaurs.