How to create Embedded Media Field: Video with custom resolution per Views field
You can set it in the template_preprocess_node() 

depending on your view mode you can set the first element :

if ($vars['view_mode'] == "full") {

   $node-&gt;video_field_name[0]['#settings']['width'] = '300';
   $node-&gt;video_field_name[0]['#settings']['height'] = '150';

}


dont forget to set all elements, not just the first one

other settings you can set:

#settings
  controls (Boolean) TRUE
  width (String) 300
  height (String) 150
  download_link (Boolean) FALSE
  download_text (String) Download


Edit:

template_preprocess_views_view_field is what you need for views probably. there you can access to the $vars['row'] with all data you need. maybe you will need to rerender the field.

If this does not work there is a workaround:
the embedded-media-field sets its settings in the drupal js-settings.
get the js settings with drupal_add_js(), find the element mediaelement and set the settings manually.