these is great feature to have and it easy for user to play a video while downloading. It also help to check the quality of video at start of the download. So it reduce unwanted downloading of waste data and also save time

you can already do this.

select a torrent and go to the files tab. right click any file and go to priority. at the bottom are the sequential choices of aggressive, on and off.

sequential not working

what tixati version and what OS?
how exactly is it not working?