If they're showing up as realplayer files then you must have RP set as the default player for that file type. If you recently d/loaded RP or updated it, it may have gotten set as the default player. It's easy enough to change back. Just open the folder with the files in and right click one of the files > properties > Change > select player you want > OK. See:
Setting Default video app
Limewire can only play audio files, so if they're video files they will play in their default player. If you want to use the LW player for audio files, open LW and go to Tools>Options>Player, and tick the box, and hit apply.
Not sure about your search result, could be you have it set not to show junk files. In LW go to Tools>Options>Filters>Junk and see if it's set not to show junk files. You can change it to display junk files. Try searching at different times of the day. As people log on and off you'll get different results.
Otherwise try these threads:
How to find music Fake files showing up in search results (Connecting for ages with many hosts & then Need More Sources when trying to download a file.)
If none of that helps, try deleting the LW preference folder. Instructions here:
Fixes for Limewire