I don't think the folder is limited to 2GB. However, in the standard ISO format used for DVDs there is a file size limit of 2GB. You can fill the entire disc with content in the extras folder if you wish, but no single file can be bigger than 2GB.

If you use UDF format then you can have significantly bigger files. However, DVDA won't burn UDF discs. You can prepare in DVDA, but you'll have to burn with some other software such as Nero.