This is how the fake Facebook post looks:
If you click on the post you will be taken to one of the following websites:
Both websites look like a fake copy of popular video sharing website Youtube.com. You will be asked to "Like" the video before you can view it, please do not.
Also, if you click on the fake looking Youtube video player, in an attempt to play the video, you will automatically "Like" the website that you are currently on.
The video that will be shown has nothing to do with the caption "At 17, she did THIS in public high school" or the photo of the young girl in the Facebook post.
The video that is shown is the trailer of a French movie called "17 ans encore bande annonce", translated to English is "17 Again trailer", on YouTube. This movie came out a few years ago.
I think the aim of this Facebook post is to trick as many people as possible into “Liking" it, so it can become popular.