Hmm... a little weird, but maybe something has changed on the server. Up until now, haven't had the 2mb max file limit error appear when uploading large files.
In this SS3 instance, I already had the following lines in the php.ini, and it obviously didn't have any effect:
upload_max_filesize = 24M
post_max_size = 24M
I had also uploaded a php.ini with those lines above in the /framework directory, and this didn't have any effect either.
I also tried following the instructions on globally overriding the UploadField_Validator variables in config.yml with the following lines, but this also didn't have any effect:
In the end, the only thing that worked for me was adding the following lines to the .htaccess:
php_value post_max_size 24M
php_value upload_max_filesize 24M