I had the same problem that you did, and I think I know why this is a problem. It basically boils down to the length of the phrase you are looking for. Unfortunately, many of the aircraft that we know are recognized by their acronyms or war numbers. (P-51, P-47, P-38, C-47, B-25, B-26, etc.) The search engine does a terrible / non-existent job recognizing these codes, although it should.
The way that I was able to find it was the word "Skytrain," which is what it was listed under. In his description, he did not use the word "Dakota," which is why your search came up blank.
In addition to The B24 Guy's method, you can try entering the username of the uploader and searching for words, but it's not foolproof. I can certainly understand your frustration.