Kivy Video Player not displaying in full screen

So I seem to be having an issue with Kivy , I have a video player added into one of my screens. I have setup the video player in the KV file with the code below

Screen:
    name: "VideoPlayer"
    id: VideoScreen
    BoxLayout:
        orientation: 'vertical'
        VideoPlayer:
            id: video_player
            allow_stretch: True
            size_hint: (1, .9)
            source: ''
            allow_fullscreen: True
            options: {'eos': 'stop'}
            keep_ratio: False
            player_state: 'play'

        Button:
            size_hint: (1,.1)
            text: "Exit"
            on_press:
                video_player.state = "stop"
                video_player.source = ""
            on_release: root.mainmenu()

However the video will not fill the box, it won't stretch when I re size the window it gets to a certain size then stops getting any bigger, as you can see from the screen shot below there is lots of room and the video should take up all that room. But it won't. What am I doing wrong?

EDIT 1::

Its even worse with an m3u8 stream

The allow_stretch option (or fit_mode) controls the stretching of the video texture. But those options must be included in the options dictionary as they are options for the underlying Video instance. Try changing:

options: {'eos': 'stop'}

to:

options: {'eos': 'stop', 'fit_mode': 'fill'}

Or you could use contain instead of fill to maintain aspect ratio.