The visualization is designed to show a video from a single data record. If your result set includes more than one data record, only the video from the first record will be shown. You should use a slicer or some other filter to limit the number of records in your report.
You can provide up to three fields that will be used to construct your video: video url, poster url and title. Of these, only video url is required. You must use the Column Mapping option before your video will display.
The video will fill the horizontal size of the visualization window. This means than the video may be stretched or shrunk to display at the requested horizontal size.
The vertical size of the video will be whatever is required to maintain the original aspect ratio with the current horizontal size. If the current window's vertical space is not large enough to display at the current requested size, the video's vertical display will be clipped. Adjust the window to your expected video size to allow the video controls to appear in their proper location, superimposed over the video.
This visualization will only display videos on the Power BI web app (https://app.powerbi.com).
It will not display videos in the Power BI Desktop client, because the Power BI Desktop client does not contain the necessary codecs to play video.