Video element always uses some predefined volume level when starting playback. It should use the value of volume property.

The volume changes to correct level if volume property is changed after playback has started.

Attached test application can be used to reproduce the issue. It plays a video named test.mp4 from the root of e-drive. Use some video which has audio. Initial volume is set to 0.9 which is quite loud. Tapping the "Volume" text on the bottom left corner of the screen changes the volume level to 0.8 which should be a little less loud.