MainActivity.kt

import com.google.android.exoplayer2.ext.cast.CastPlayer
...

private lateinit var castPlayer: CastPlayer
val videoString = "http://cbsnewshd-lh.akamaihd.net/i/CBSNHD_7@199302/index_700_av-p.m3u8"
.....

castPlayer = CastPlayer(CastContext.getSharedInstance(this))
castPlayer.setSessionAvailabilityListener(object : CastPlayer.SessionAvailabilityListener {
    override fun onCastSessionAvailable() {
        castPlayer.loadItem(buildMediaQueueItem(videoString),0)
    }
    override fun onCastSessionUnavailable(){
     // Todo
    }
})
...

private fun buildMediaQueueItem(video :String): MediaQueueItem {
    val movieMetadata = MediaMetadata(MediaMetadata.MEDIA_TYPE_MOVIE)
    movieMetadata.putString(MediaMetadata.KEY_TITLE, "CBSN News")
    val mediaInfo = MediaInfo.Builder(Uri.parse(video).toString())
            .setStreamType(MediaInfo.STREAM_TYPE_BUFFERED).setContentType(MimeTypes.APPLICATION_M3U8)
            .setMetadata(movieMetadata).build()
    return MediaQueueItem.Builder(mediaInfo).build()
}