1. You did not download the movie 'from' LimeWire, but another user like yourself.
Gnutella network is peer to peer sharing = sharing files between person to person, no central servers.
2. For video playback, you are probably missing the correct video codecs. We normally recommend using VLC player as it has in-built codecs & will play most valid videos you download;
CODECs list for Movies / Alternate players.
VLC - (click on link) _ (choose nearest mirror site)