What files does this backup? (program files, system32 etc?)
How do you restore the files if and when all goes wrong?
Welcome to the forum! 
http://forum.avast.com/index.php?topic=22813.0
From the help-file:
If a file is infected by a virus, it may be possible to repair it using the information stored in VRDB, i.e. turn it to its original state.
So I think the avast-program is taking care of the repairing, I am not sure, I haven’t needed to repair anything yet…
Wait, so you can, repair files, incase they are system files?!
http://i112.photobucket.com/albums/n177/JaidenUchiha/untitled.png
WOW! Thats great, because here, is what I have so far, and im afraid to delete them because im in trouble if they are system files.
I wonder whats up with this Win32/Jeefo crap…
http://forum.avast.com/index.php?topic=4818.msg34783#msg34783
It stores the necessary info to restore executables (*.exe, *.com) files.
VRDB is not a backup system, the stored information is very small (not the whole files).
Besides, only Win32 executables are processed.
The VRDB data are stored in \Data\Integ\avast.int
So it’s not a bakcup utility, but a restore feature of avast.
VRDB is a generic method, storing file parts that are often target of virus infections. So, it is capable of fixing even some brand new virus infections.
Please correct me if I’m wrong, but a detailed technical description how the VRDB uses the filesignatures to repair damaged files has yet to be delivered. Personally I can imagine the the VRDB holds fingerprints/checksums of the files and the start and end of the files (somehow). So if a file is infected by a virus, avast knows exactly how to strip the virus of the file to get it intact again.
But this is pure speculation and was never confirmed by avast support techs here.
I was not here at the forums for a long time, so maybe this has been confirmed. But I did not find anything.
Maybe they can post more info…