My daughter is pretty smart. The other day I was getting on her case for watching too much YouTube at her computer, which is a problem I'm sure more than a few parents face. She had the perfect response for me, though: "But Dad, I'm using YouTube to study English!" She had rightly calculated that her former ESL-teaching father couldn't forbid an activity that helped improve language skills, and I sheepishly let her get back to her shows. Having access to American TV through the Internet has given her a lot of exposure to new words and phrases, and she often comes to me with questions about what certain words mean, like the following exchange from an episode of Teen Titans that was giving her trouble:
Beast Boy: Why are ducks so funny? Because they're always "quacking" jokes.
Starfire: Oh I see. It is humorous because ducks lack the large brain necessary for the telling of jokes.
Most of us study foreign languages by learning grammar and vocabulary through language textbooks, and every time your brain learns a new concept, a physical change occurs. For example, if I teach you that the Japanese word for umbrella is kasa and you remember it, a synaptic bridge will have been built in your brain linking these ideas, perhaps cross-referencing it with the Spanish word for "house" (casa) since the pronunciation is the same. In the case of my daughter, however, the English and Japanese sides of her brain often seem to grow separately, and so she's able to use both languages well but often has no idea what a given word means in the other language.
My daughter is learning English through YouTube.