Because a PC has a static IP address (unlike mobile data that rotates), copyright trolls easily trace torrenting activity. If MKVCinemas uses a P2P (Peer-to-Peer) fallback for slow downloads, your PC automatically uploads pieces of the movie to other users. This uploading is what gets you sued for distribution , which carries fines up to $150,000 per title in the US and €750 in the EU.
While the process sounds straightforward, using exposes you to significant dangers that mobile users might avoid. mkvcinemas.com pc