Did you also go to yoursite.tld/admin/settings.php , aAnd changed the "The max upload filesize for premium users (in bytes)" to: 1048576000
I'm not sure if this is needed, but did you also restart Apache to make it re-read the php.ini file?
If so, and it still does not work, you should maybe wait for Adam (the admin here). He might know what could cause this I'm only a user...