Now that you have a movie or series episode downloaded you can choose what app you want to play it in.
VLC media player is a good choice because it doesn't rely on what codecs you may or may not have installed on whatever system, VLC is free. There are others for free if you prefer something else, here is a link to a web page with info and reviews of several players, the same link is on all the movie pages VLC alternatives showing quite a few good alternatives to VLC with links to the relevant websites.
The MKV format is the latest generation format for audio/video files. Strictly speaking MKV is the container it is known as Matroska and is free open source unlike MP3 and MP4 where browser developers such as Google, Mozilla, Safari and Opera etc. are required to pay royalties to include their codecs.
MKV is better quality and smaller file sizes than its predecessors and the container is also capable of holding more items such as subtitles for example.
MKV is fast becoming the new standard for audio/video and will for sure become the leader of the pack.
If your telly or perhaps satellite box has a USB port and most of them have these days, you could put your download onto a USB stick or external hard drive and play it back directly on your telly without a computer. It may not be able to play MKV files unless it is pretty new but MP4 should be a breeze.ALL FAQ's