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