How many of you have seen this video by now?
Yes, it's goofy. Yes, my kids love it - I love it, too!
I've heard quite a number of people exclaim that it's pointless because of course foxes have sounds they make, and this misrepresents them as not having sounds of their own. Just for a second, let's set aside the fact that the video is intended to be humorous, and let's talk about the underlying question.
When I first listened to it, I immediately thought about onomatopoeia. This is of course what the whole opening of the song is about: "Dog goes woof, cat goes meow, bird goes tweet and mouse goes squeak..." If you think about it, these onomatopoetic animal sounds are some of the earliest things we learn as kids. It's no coincidence that the song's video features a grandfather sitting with his grandson and a giant book! But you don't find fox onomatopoeia in this context. Foxes tend to do one of two things: either they are silent, or they speak like humans do. It's certainly a testament to the fox's slyness that it's attributed with human speech, which fits quite well with its trickster qualities (and of course there are many myths that have the fox transforming itself into human shape, too).
Today I also read this article at Wired magazine, which says, interestingly enough, that there is some similarity between the song's proposed fox sounds and the actual sounds of foxes. It even gives you the recorded fox sounds for the comparison...and I see their point. It's very similar to what I did when I was writing "At Cross Purposes" for Analog, and I wanted to design a language for aliens who resembled otters. I went online and found recorded sounds of otters, then tried to render that in human phonemes that could be written with the Roman alphabet. It wasn't entirely straightforward! However, it did give the language a great feel that really fit with the other aspects of these aliens.
The other question of onomatopoeia for writers, of course, is whether to use it when we write. Well, don't worry - you are already using it! Not all onomatopoeia is as obvious as bow-wow or meow. The words "knock," "screech" and "splash" are all onomatopoetic but don't stick out really obviously from the flow of English text. The question of whether you should say "Bang!" instead of remarking that your character heard a shot ring out is a good one, however. As usual, the answer is, "if it works." Some prose styles require a kind of flow and fluidity that wouldn't fit well with a sudden break filled with an onomatopoetic flourish. On the other hand, deep POV often cleaves very closely to the perceptions of a protagonist as they happen, which means that including onomatopoeia for sounds that interrupt that character's concentration or catch their attention can work far better. They really amount to an example of "showing, not telling" in that case.
It's something to think about. And in the meantime, I hope you enjoy the song!