You have to buy new extended license every time you want to include it in a new theme.
Its best to ask these questions the author directly, somewhere in the comments of the file or through his other support channel, if exist.
I got my money on moneybookers yesterday.
There is an error in console when you try to run vimeo:
Uncaught TypeError: Cannot read property ‘2’ of null
Wherever its coming from hopefully it gets fixed soon.
Things are that easy as you might think. You are mentioning video and audio files. If you want to have video and audio files, you will need to have multiple file formats because not all browsers support just single file format. On top of that, reading directories for file names makes your job that much harder because for every mp4 video file you need to have ogv pair, and for every mp3 audio file you need to have ogg pair, and they need to be named the same.
You should ask these questions directly to the author in the comments of the file you bought.