Edit in JSFiddle

/*
    JS library reference:
    https://github.com/bistri/bistri-conference-js
*/

var localStream;

// initialize API client with application keys
// if you don't have your own, you can get them at:
// https://api.developers.bistri.com/login
bc.init ( {
  appId: "38077edb",
  appKey: "4f304359baa6d0fd1f9106aaeb116f33"
} );

// test if the browser is WebRTC compatible
if ( !bc.isCompatible () )
{
  // if the browser is not compatible, display an alert
  alert ( "your browser is not WebRTC compatible !" );
}
else
{

  /* Set events handler */

  // when local user is connected to the server
  bc.signaling.bind ( "connected", function ()
                     {
    // ask the user to access to his webcam and set the resolution to 320x240
    bc.startStream ( {audio: true, video:true}, function( stream )
                    {
      // set "localStream" variable with the local stream
      localStream = stream;

      // insert the local webcam stream into the page DOM
      bc.attachStream ( stream, document.body, { mirror: true } );

      // join a conference room called "conference_demo"
      bc.joinRoom ( "conference_demo" );
    } );
  } );

  // when the user has joined a room
  bc.signaling.bind ( "joinedRoom", function ( result )
                     {
    // then, for every single members already present in the room ...
    result.members.forEach ( function ( member )
                            {
      // ... request a call
      bc.call ( member.id, "conference_demo", { stream: localStream } );
    } )
  });

  // when a new remote stream is received
  bc.streams.bind ( "streamAdded", function ( remoteStream )
                   {
    // insert the new remote stream into the page DOM
    bc.attachStream ( remoteStream, document.body );
  } );
  
  // when a new remote stream is received
  bc.streams.bind ( "streamUpdated", function ( remoteStream )
  {
    // reattach the remote stream 
    bc.reattachStream ( remoteStream );
  } );

  // when a stream has been stopped
  bc.streams.bind( "streamClosed", function ( stream )
                  {
    // remove the stream from the page
    bc.detachStream ( stream );
  } );

  // open a new session on the server
  bc.connect();
}

video {
    width: 320px;
}