Using WordPress 3.6’s own video shortcode

If you wish to use the [video] shortcode included in WordPress 3.6 instead of Themify's own video shortcode, you can follow these steps:

1. Create a file named custom-functions.php in your theme root folder
2. Edit it, and paste the following

remove_shortcode( 'video' );
add_shortcode( 'video', apply_filters( 'wp_video_shortcode_handler', 'wp_video_shortcode' ) );

3. Save the file. If you were editing it locally, upload it by FTP to the theme folder in your server.
4. in WP Admin, go to Themify > Styling > Custom CSS
5. paste this

.mejs-container, .wp-video-shortcode {
    max-width: 100% !important;

6. save and check your site.