Update 6407 fails

Upgrading from 5.x-1.5 to 6.x-4.2-beta2

Update #6407

* Failed: ALTER TABLE {video_files} DROP filesize
* Failed: ALTER TABLE {video_files} DROP filename
* Failed: ALTER TABLE {video_files} DROP filepath
* Failed: ALTER TABLE {video_files} DROP filemime
* Failed: ALTER TABLE {video_files} ADD data longtext

* user warning: Can't DROP 'filesize'; check that column/key exists query: ALTER TABLE video_files DROP filesize in C:\wamp\www\drupal6\includes\database.mysql-common.inc on line 331.
* user warning: Can't DROP 'filename'; check that column/key exists query: ALTER TABLE video_files DROP filename in C:\wamp\www\drupal6\includes\database.mysql-common.inc on line 331.
* user warning: Can't DROP 'filepath'; check that column/key exists query: ALTER TABLE video_files DROP filepath in C:\wamp\www\drupal6\includes\database.mysql-common.inc on line 331.
* user warning: Can't DROP 'filemime'; check that column/key exists query: ALTER TABLE video_files DROP filemime in C:\wamp\www\drupal6\includes\database.mysql-common.inc on line 331.
* user warning: Duplicate column name 'data' query: ALTER TABLE video_files ADD data longtext in C:\wamp\www\drupal6\update.php on line 69.