Great idea Jordy - This sort of plugin is badly needed since the others all have bugs with 3.6 etc - and don't seem to be supported any longer.
Posting this for information and marking status as not a support issue - something to look into for a future update maybe.
There's a few bugs - they may be specific to the installations I've tested the plugin with. This is probably the most serious if users aren't careful to test things before deleting a lot of files
The uploads/wpmc-trash folder is not getting created when deleting a file.
Checked this on 2 live sites, on different servers - the files just get deleted.
Both Apache 2.2.23, PHP version 5.2.17, MySQL version 5.1.70-cll
However, on a local host testing mirror for both these sites, the folder was created. (same local host server for both). Looks like the folder is only created when deleting a file, not when the plugin is installed/activated.
Must be something with the server setups (one is on shared hosting with Hostgator), the other may be mod_security settings.
There's no errors relating to this in WordPress or server error logs.
1. Tried changing wp-content/upload/ folder permissions to 777 - made no difference
2. Tried manually adding the wpmc-trash folder - Files still got permanently deleted, not moved to trash folder.
Just as well I'm careful to test things first, and have backups :)
Quick heads up on other issues - (VERY SPECIFIC to the sites I've tried the plugin on)
Doesn't recognize files attached to (some) theme custom content types (Gorilla Themes)
Doesn't recognize files attached as open graph images (not in content body or featured image, and in special folder)
Also may be worth looking at for future updates.