You need some codecs for the files to play properly.
See:
CODECs list for Movies/Alternate players / Video help forums/ video-mp3 fixers
Try using
VLC media player, it has the codecs built in and will play most file types.
For WMP try
K-Litecode Codec Pack or
XP Codec Pack 2.0.6.
If your OS is Vista:
Vista Codec Package v4.4.8 (freeware).
Needs more sources means just that. It can't find any sources to d/load the file from. That usually means the file is junk/spam, but it could also mean that noone is connected who has the file.
Before d/loading videos, check them with
Bitzi Web Lookup. It'll help you sort out the good ones. While on the Bitzi site, search for the file there and use the magnet link to start the d/load in limewire. Then search for it again in LW to help find some sources for the file.
Also preview the file when it gets to 10-15% to check that it's what the title says and not mislabeled porn.
See:
Fake files showing up in search results
Also:
Problems with the search How to find music(and video)