A while ago I did this for webtop (Video streaming from Webtop) which was later published by EMC as a white paper. This is a similar attempt using an external widget on D2.
In this case, I’ve used video.js, a free Javascript video player. The widget itself is quite straightforward, just create a normal external widget, register the D2_EVENT_SELECT_OBJECT and configure the external widget sending via parameter the user name, the repository and the session ticket. Once this is done, you just have to get the r_object_id of the selected document, set that value on the video object via JS, and just enjoy.
You can check the full on code on GitHub.
Alvaro de Andres' Blog 
Thank you, Aldago! This works perfectly in D2. However, I have a question unrelated to D2: have you experienced issues with video playback? Specifically, I’m having trouble with the skip forward and backward features — they aren’t functioning for me.
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No, but you can try any other JS player, it should work with any of them
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What do you use to stream the videos to the custom widget? How do you handle the ranges? I’m using dctm rest.
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As shown in the code, this is done by retrieving the ACS link to the file, as ACS provides streaming capabilities. Nothing else is needed.
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