torrent poster: support m4v
torrent poster: support m4v

feross/webtorrent-desktop,webtorrent/webtorrent-desktop,feross/webtorrent-desktop,yciabaud/webtorrent-desktop,feross/webtorrent-desktop,michaelgeorgeattard/webtorrent-desktop,feross/webtorrent-app,michaelgeorgeattard/webtorrent-desktop,feross/webtorrent-app,webtorrent/webtorrent-desktop,feross/webtorrent-app,michaelgeorgeattard/webtorrent-desktop,yciabaud/webtorrent-desktop,webtorrent/webtorrent-desktop,yciabaud/webtorrent-desktop