Why wouldn't it be? It is still streaming and it will start playing the video soon after you hit the play button instead of downloading the entire video first. The only difference is that it will be caching the download for a certain period of time and possibly downloading rare chunks with extra bandwidth ahead of when the chunks are actually needed. The truth is though, if the torrent is not top heavy with seeders then it is no good anyway so I don't really get why people are so focused on rare chunks.
