Very basic component copied from the example code does not accept the src prop

```
Warning: Failed prop type: The prop `src` is marked as required in `BackgroundVideo`, but its value is `undefined`.
in BackgroundVideo (at App.js:15)
in App
in AppContainer (at src/index.js:21)
```

Here's my small component, I've copied the src prop straight from the test.js file

```javascript
import React from 'react';
import BackgroundVideo from 'react-background-video-player';

export default function Hero() {
return (

)
}
```

Can you provide an example with a very basic setup using a function rather than a class component?
Thank you very much.