Sounds like, you have defined source of video. With it, you can play video:
1. WPF app using MediaElement
<MediaElement Source="http://yourwebsite/yourvideo.mp4" LoadedBehavior="Manual" Name="mePlayer" />
Refer:
Playing video - The complete WPF tutorial[
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2. HTML5 using video tag
<video width="320" height="240" controls="">
<source src="url-to-video.mp4" type="video/mp4"></source>
</video>
try out!