It depends. In some countries, streaming copyrighted content for free is considered piracy. But in other countries, it's not considered illegal as long as you're not downloading the content. You must check your country's laws before streaming copyrighted content on FlixTor or any other free streaming site.
Also, I recommend using a VPN while free streaming on FlixTor or any other free streaming site. A VPN will help you stream content anonymously and prevent your ISP from tracking your online activity.