1. The viral videos of "dragon sightings" are obviously just CGI (or maybe it could be the way the dragon works)
2. From the test pictures I saw, the dragon had an airplane propeller, parachute and pilot. I don't think anybody will believe that it is a flying dragon if we can obviously see these parts.
3. Remember the last time Disney made an incredibly ambitious, lifelike dragon?
(Just so you know this so called "dragon expert" Disney is using in their viral marketing is says that this dragon is a friendly guardian of Fantasyland and not related to Maleficent (or maybe?...))
If you look at this video, you can still hear the dragon's propellers even though you can't see him.