PHP Fatal error: Class 'S3' not found in mm_s3

This module has so much potential, but I'm having some problems trying to set up media mover along with Mediafront and OSM Player to handle transfer to and playback from Amazon S3.

If I set up Media Mover on a fresh install I get the S3 test to work, but on enabling the Mediafront modules I get this error:

PHP Fatal error: Class 'S3' not found in /path_to_modules/media_mover/contrib/mm_s3/mm_s3.module on line 138, referer: http://www.domain.com/admin/build/media_mover/tests/mm_s3

If I disable Mediafront modules, the error remains. Using Mediafront 6.x-1.0-rc5 and Media Mover 6.x-1.0-beta8, but I get the same errors in beta7 and beta 6.

On a different Drupal setup I also get this error:

PHP Fatal error: Call to undefined function media_mover_api_configurations_sync_code() in /path_to_modules</media_mover/media_mover_ui/media_mover_ui.module on line 1161, referer: http://www.domain.com/admin/build/media_mover/tests/mm_s3

Thanks for any help.