Purpose of TVnzb feature is to autodownload&import nzb files posted at
www.tvnzb.com based on certain parametars provided at filters list.
So, filters list is there to decide which nzb file will be downloaded and not to filter displayed list of nzb. To test this feature do this:
In filters list add:
*galactica* | A
Set list to new (tvnzb carries two list new-only new releases and old-old releses), clear display results, set timer to 10min and enable timer. After 10min program will refresh New list and in list among other things will be latest Batlestar.Galactica nzb. Since program sees all items on the list as new items (previously there was no item in the list - we cleared the list) it will start applying filters against every new(in our case all) item. Based on our filter list only nzb which contain substring galactica is Allowed to be downloaded, program will autodownload & import that nzb.
Smart thing to do would be to first refresh New list and then turn timer on. That way all the items on the list are old to program and when the program refreshes list, new items posted to tvnzb between last refresh and current one are displayed at the top of the list and only those items are checked against filters. When all done, all items are now old to program and after 10 min it will repeat whole procedure.
Practical usage is to leave program to download series you like and you know that will be released during night or while you're away.
If there is something unexplained after this, freely ask