Hello
First let me give you a link to the extensive user manual for this DVR here it is:
http://www.aactionalarms.com/manuals/Speco/DVR%204TN-8TN-16TN%20manual.doc

As to your question about digital dump, here is how you dump recorded data, it is outlined in section 4.5 of the user manual;

Deleting Recorded Video

The user can delete recorded video in the Purge Data menu. The administrator password is required to access the function. Select from Main menu, once in the Record Setup menu, move the cursor to and press ENTER; the Purge Data menu is displayed.

Purge Data

1. Purge All Data

2. Purge All Event Data

3. Purge Event Before

4. Start to Purge

NO

NO

2000/01/01

NO

Purge All Data

Select this item to delete all normal recorded video from the database.

Purge All Event Data

Select this item to delete all event video from the database.

Purge Event Before

This item is used to delete event video that was recorded before a specific date.

As to the 2nd question, the data is not backed up to a central location unless you do it manually using the storage option available