These youtube videos are likely under the impression that fairies are physical beings.
They are not. Those of us that work with such beings (and by proxy, believe in them in our personal theology) know that they are spirits without physical form.
Traditionally, faeries are a range of spirits. Some are of nature, land wights and spirits of the environment. Others are perhaps the spirits of our ancestors or an ancestral race, which is prominent in my ancestor worship.
You don't simply become fey. At least in my theology, you could be considered one as you join the ancestral dead.