I'm not including the people that actually try fix their situation. If you're depressed but you tell someone (that you know, internet doesn't count); I completely understand.
Posting a YouTube video isn't going to help, to me it just seems like a cry for attention. Why would you do it? If you're telling me that;
All of her teachers hate her.
Her parents hate her.
She has no friends whatsoever.
Nobody helps her.
She can call childline or something. People who when they tell someone and just want sympathy (the attention kind, mercy is a different thing) disgust me and this is what this feels like, assuming it's not faked which it could may be.
Also; if you're going to actually want help you don't smile and hold up talk cards while playing a sad song like some people do. You talk to the camera (even though posting it on the internet is silly). People who do this obviously just seem to want attention. It's sad really.
EDIT; It's like if someone is physically sick. Imagine if instead of telling their parents or whatever so they could get medicine, they post a YouTube video about it to a sad song and with cards. If depression is what you say it is, a serious illness then this is basically the same thing. If you think that posting a video on the internet is better than telling someone with illnesses, you ARE crazy.