Filter view by user reference

In your node template you check the current user's uid against the view reference field's data. If it matches you print out the file stuff, if not... then do nothing. Doesn't get any easier.

I'm not sure you even have to use this module? Files aren't nodes, and this is node access, not file access. But you could use an idea like this in your node-your_content_type.tpl.php template:

<?php

global $user;  // get current user

$show_files = FALSE;  // assume he is not allowed to see files

foreach ($node->field_allowed_users as $allowed_user) {  // check each allowed user in a userreference field called 'Allowed users'
  if ($allowed_user['uid'] == $user->uid) {  // test if the allowed user matches the current user
    $show_files = TRUE;  // assert this person is allowed to see files
    break;   // stop this foreach loop now that we have found the person
  } 
}

if ($show_files) {  // test whether we decided to show files or not in the previous bit
  print "file stuff";  // sorry dunno this bit
}

?>