Syncplay

Syncplay can automatically synchronize video playback for two or more users, so that you can enjoy watching a movie together with your friends, regardless of location. With its help, the state of multiple media players can be kept in sync at all times, so that users can watch the same thing at the same time.

Sync video playback across multiple PCs

The application provides support for a few popular players, namely VLC Media Player, Media Player Classic - Home Cinema (MPC-HC), mplayer2 and mpv.
Based on a client-server architecture, it creates virtual rooms on the hosted server, synchronizing all the players of connected users. There are public servers available, but users that are concerned with privacy protection will be glad to find out that they can host their own password-protected server.
Syncplay is only designed to sync playback of media player, but it does not provide video streaming options and is not capable of detecting the opened file. However, each client application can be instructed to send raw or hashed information related to the loaded video file to the server, which warns users about duration and file mismatches.

Replicates pause and unpause commands

The principle Syncplay relies on is simple: the server keeps track of the playback position for all participants, sending synchronization commands to the client applications for pauses, unpauses and position changes. Any new user who joins the room is brought to the shared playback state.
Syncplay can be configured to automatically slow down playback in case the others are falling behind, pause when a user gets disconnected and rewind the video if major desynchornizations are detected. Note that it only synchronizes video playback and does not interfere with the player configuration at all.

Enjoy a synced playback experience

Syncplay is an interesting application that enables you to enjoy a movie together with your friends, even if they are miles away. As a drawback, it does not provide a chat area for you to talk to all the other participants in the virtual room, so a third party program is needed to do so.