Live DVR seek to live isn't universally handled like that unfortunately. Right now the only scenario that videojs could encounter seek to live is with the HLS plugin. Per HLS spec the live point in the stream is akin to duration - (3 * buffer). The reason I did it this was to stub it out for the various plugins to add handers for. 

i.e. in HLS player.on('seeklive', function(){ player.currentTime(player.duration()-(3*player.bufferMax))
});