BeTheme Demo Data is best choice for single demos and single homepages. But if you want to add ALL, then you must download xml file from http://themes.muffingroup.com/xmls/ but you must to know that this file is also not complete because we are not able to add more and more staff inside this file because servers won`t accept it. At this moment this file is very big and that`s why we can`t add more demos on it. And this is the main reason why we decided to create single demos. Pages are smaller, can be uploaded easily on any server and in our and customers opinion this is much better way to import pages. In your case we recommend to upload staff from BeTheme Demo Data section but without media. This should work for you definitely.
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can you explain what you want to import? ALL demo stuff or one of the demos? If one demo, then please tell us which exactly and we`ll try to help.
1. Again upload .xml file called <i>betheme _ALL.xml</i> but without media. Images you will upload manually.
2. Upload the rest of .xml files included into package except <i>betheme _ALL.xml</i>
3. Split <i>betheme _ALL.xml</i> file on smaller parts so you can cheat your limits. For splitting this file you can use tool that has been explained on http://wordpress.org/support/topic/problem-importing-wordpresscom-xml-files or http://wordpress.stackexchange.com/questions/113055/import-wordpress-xml-file-larger-than-8mb
4. Contact with your hosting provider and ask he can change your limits so you will be able to upload more that now.
Hope this explanation will help you a lot