Browsers can't make torrent connections, or any others for that matter. Except for HTTP and WebRTC.
WebTorrent is a hack to run torrent protocol over WebRTC, but obviously it only connects to other WebTorrent programs and not to normal torrent programs. I think PeerTube uses it.
Imo downloading on the server is more useful. Web torrent is great but I don't think it's very practical in many places.