Syncplay synchronizes the playback of media files across several
remote machines. The Syncplay Client launches a media player on a
user's computer, connects to a Syncplay server and join a virtual
room on that server. Pauses, unpauses and seeks made within that
media player instance are relayed to fellow viewers via the server
to allow for these actions to be replicated by the media players
of everyone else in the same virtual room.

WWW: http://syncplay.pl/