Fixing the player initialisation when the media element has a height of 100%.

The MooToolsAdapter does not support the jQuery parent method. Instead getParent has to be used.
I'm not familiar with MooTools or with this adapter you're using, but this seems to work. I also had to add the following CSS to get all the elements to display nicely:
```css
.mejs-layers  .mejs-poster, .mejs-layers .mejs-overlay {
    width: 100%;
}
```
I'm assuming that the JS code should somehow add this to these elements (it seems to work with the height but not with the width), that's why I'm not including it in this PR.