There are two things I can think of that may be causing the problem. First is that you're trying to PLAY the clips from a source that isn't set up for it. If this is the case, you should try to right click and save the file to your system. They should be okay from there since no network connection is needed. Second is that you may have access blocked if you're using a firewall. (I personally keep my media player ports blocked and manually turn them on only when I'm using them.) You may need to check/change your settings to open access.
Ann