I didn't find the minoura accessory thing to be very strong (broke while I was riding with it and I lost a light - to be fair, I had hit a fairly large pothole before the weak point snapped).
Bdop's dashboard genie (and one of the knockoffs) has been much more secure for me and would be more likely a place I'd put an expensive camera.
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Bikes: 1996 Eddy Merckx Titanium EX, 1989/90 Colnago Super(issimo?) Piu(?), 1990 Concorde Aquila(hit by car while riding), others in build queue "when I get the time"