Is a small wind tunnel, like in the video, of any value for building planes able to carry a man?
The short answer is NO!
To be more clear if, as an example, one has a small wing and measures its drag coefficient, with the help of a small wind tunnel, this coefficient is simply useless for a wing of the same shape but with a surface: 25, 50, 100 times larger.
"Scaling from the tunnel to the Wright Flyer ... showed the Wrights’ drag prediction to be 300% too high, resulting in highly inaccurate efficiency predictions. ... the Wrights’ quantitative data was not applicable to full scale design." (From the study of Michael Gary Dodson)
The Wright Brothers just wasted their time with the wind tunnel they had built. They could not have used the numerical data obtained from such experiments for designing large wings.
The two inventors from Dayton just copied the Voisin - Farman - Delagrange wings, which they saw in 1907 when they spent about 6 months in Europe, and then built a plane in 1908, powered by a French engine, Bariquand et Marre, and flew for the first time near the town of Le Mans, on August 8, 1908.
For more information you can read this new free book:
A. I. Root, the liar number four after the Wright Brothers and their mentor, Octave Chanute
The main two witnesses of the Wrights, Amos Ives Root, from Medina, Ohio and Octave Chanute from Chicago did not see the two inventors flying on September 20, 1904, and October 15, 1904, respectively, as they claimed.
The December 17, 1904, "successful" trials performed near Kitty Hawk (an isolated place far from civilization) represent nothing in comparison with the 105 flights at Huffman Prairies (near Dayton), claimed by the two brothers for the year 1904. No credible witness saw them flying that year.