Martin Collinson's Ivorybill article
Recently published here.
In short: Same fatal mistakes as made by Sibley et al.
-- He interprets artifacts as plumage. As I have pointed out several times here, the Luneau bird shows black fringes on the leading edge of the underwing as often as it shows black fringes on the trailing edge of the underwing. Ergo, apparent black fringes must not be taken to indicate anything about the bird's actual coloration. There is nothing resolved in the underwing pattern but a lot of white with a black area at the tip, which both species share.
ADDENDUM: I have just frame-by-framed through the Luneau video one more time. In almost every single case, every black fringe seen on the birds wings can be seen to align with a darker area in the background. When this happens the black fringes often occur on both edges of the wings, and in subsequent frames if they reappear they do so fixed relative to the background, not relative to the moving wings. The only exceptions to this are the small black wingtip area, which appears most consistently at full downward extension. The supposed broad curving black area in frame 366.7 that is said to represent the outer portion of the black trailing edge of a PIWO is exactly aligned with the background shadow, and it disappears on the next frame when the wing has moved past this shadow. The black arcs a the ends of the wing in frame 300 are (on the right wing) aligned with a background shadow and (on the left wing) clearly a streak left by a rapidly moving wingtip. There is no consistent occurence of a black trailing edge or curved black wingtip; these things appear for one frame at a time and then disappear in the next frame because they are not real. Collinson has stated on his blog that "Sibley et al. have shown why the Luneau bird wasn't an Ivory-bill." This is only true if you accept video artifacts as reality.
-- He totally misses the boat on flight mechanics (as has virtually everyone else) by focusing on wingbeat rate. There is a much bigger story, in that the shape of the Luneau bird's wing strokes are markedly different from that shown by the Nolin video or any other video of a Pileated I have seen. The Luneau bird does not fully extend its wings at the top of the upstroke, and holds them in a strong downwardly-bowed arc on every downstroke. ALL pileated videos I have seen show wings that are fully extended on completion of the upstroke and held essentially straight out downstroke on every wingbeat other than the first one or two after launch (while the bird is still rolling to attain proper flight attitude). This is very evident in Collinson's side-by-side frame comparisons, and Sibley's sketches showed these dynamics as well. Yet neither of these authors have made any mention of it nor offered any explanation. Is this flight Ivorybill-ish? No one can say, we have no comparison material. But it is definitely not at all Pileated-like. The wingbeat rate issue is minor in comparison.
My longer discussions of these isues are here and here, for starters.