There are multiple reasons why you might not be able to stream videos from torrents.
Unsupported format (CODEC): This happens when you try to stream or play a video or audio format that is not supported by in built player.
Low number of seeders: Seeders are those who continue to share the file after it has been downloaded. The more seeders there are, the faster the stream will be. Try downloading torrents with many seeders.
Low number of peers: Peers are those who download and upload the file at the same time. The more peers there are, the faster the download will be. Try streaming torrents with many peers.High number of leechers: Leechers are those who download the file but do not share it. Files with a lot of leechers will slow down your stream speed. Avoid files with a lot of leechers.Slow internet speed: Check your Wi-Fi interference, your current client version, and your client’s speed settings to improve your internet speed.
Not enough trackers: Consider adding more trackers to your torrent client.Blocked by ISP: This means your network is blocking torrent files or blocking your outgoing port (To check this, try downloading a torrent on another network. If it works, then your ISP is blocking). To fix this issue, you need to change your port number or use a VPN.
Hardware limitations: If you are downloading high-quality formats that are not supported by your hardware, then you will not be able to stream them. In this case, you need to download a dedicated player from the app store and get the stream link from the 
Torrent Pro app and paste it into the dedicated player.