if you download porn, stick to .avi or .mpg files. That goes for all kinds of videos, porn or not.

There are very rarely any usable files of other formats, and how many you can download depends on available hosts, spam results (probably more with popular stuff than porn), available bandwidth from the hosts side etc.

If you can download some and not others, it's probably not a problem with your setup, but rather the things I mentioned above. The **/** numbers imply that the rest are left out, either because they are listed as spam (in preferences you can choose to show all results) or because you filtered them somehow (like excluding certain filetypes, which would be the correct thing to do)

I don't know about the corruption settings or if there are any, so can't help you there.