Ok I was downloading this video, and when it finished downloading and I played it in my windows media player, a little notice came up saying, "Windows media player could not play this file. One or more codecs required to play this file could not be found." First of all, what is a codec? And second, what does this mean?

Go here CODECs list and alternate players for Movies & click on the CODEC link here & it will tell you what a codec is. Also there's links for codecs. Might I also suggest you get a backup player with built-in codecs such as VLC: http://www.videolan.org/vlc/ (choose nearest mirror site) & this program will no doubt be able to play the video.

How can you play videos/movies in the VLC player after you get it from limewire?

There's 2 ways. 1. (a) You can open VLC & go to menu File>Open & direct it to where your LW downld folder is. By default it's usually here: C:\Documents and Settings\"your account name"\Shared

(b) Or move the video elsewhere that you can easily find. Go to LW's Library window & select Saved Files folder & press the Explore button which will open the folder for you. Then move it somewhere easy to direct VLC to open.

(c) OR open VLC & then you can drag & drop the video onto the VLC program interface. I think you can also do this from the LW Library window also!

2. Or you can make VLC your default for playing videos so it plays when you launch a video via LW. See Setting Default video app