WMV is Microsoft's proprietary video format. Most likely, Android does not have a codec for it. You must convert it to something standard, like H264.
Unfortunately, video encoding is a minefield of proprietary technology. There are several open source converters. FFMPEG is probably the most extensive. There a convenient graphical interface for this is called WinFF (if you use windows).
You can test your HTML file by placing it and your video on an SD card and see if it works in its simplest form. Try using different video formats as a health check.
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