I haven't found a global setting, though this is very easy to do for video streaming.
Just select the torrent, then the files tab in the info box down below. Right click the file you want to download sequentially, go to priority, and check the sequential box.
You can also made this selection when you first load a torrent in, by right clicking on the file and doing the same process.
Here's a screenshot of the menu location, just make sure that box is ticked https://i.imgur.com/qF3wM6l.png
Vlc media player is able to stream these torrents as they download. Just wait until there's a decent chunk of completed download at the start, find the file and open with vlc.
Before you start up, always make sure there's a solid chunk of consecutive pieces at the start. Also, just like any streaming, your internet will have to be fast enough to download the file faster than you watch it.
This is my first post on this forum btw so hope I didn't break any rules or anything. Been a long time user though, and tixati + vlc is a great way to stream video files.