The Media Browser does not work with a physical path, but with the file managed table, and Drupal file system uses the uri of the file to get to the actual file on disk.
Go to the views settings page admin/structure/views/settings and turn on 'Show the SQL query'.
Then open up the media browser and look at the SQL query. It starts of with
SELECT file_managed.timestamp AS file_managed_timestamp, file_managed.fid AS fid, SUM(file_usage.count) AS file_usage_count
FROM
{file_managed} file_managed
which means it is using the file_managed table as its base. That comes from the file module in Core. Looking at that table definition in PHPMyAdmin for instance will reveal a fid as the primary identifier, a filename, a uri, filemime and some other fields. The uri is the important part as it tells Drupal how to get to files.
I think that if you want to include files that reside on other systems you will need to include a stream wrapper for that file system. It is explained here and here, and there is a module called Remote stream wrapper that might help