Interesting hypothesis. Some observations: (1) Danish is not a "mother tongue" of English. English is a West Germanic language and Danish is a North Germanic one. English is most closely related to Frisian and more distantly to Dutch. Vikings did influence Old English during the 8th and 9th centuries CE. (2) Fugleman is cited by the OED starting in the first decade of the 19th century. One would have to explain how an Old Norse word lay dormant in English for about a millennium before surfacing again. The German word Flügelmann is appears around this time in Goethe. On the other hand, I have seen the silent ethnographic film you speak of, and it is truly impressive.

Ceci n'est pas un seing.