Hi, @abhishek did you find any solution for this issue? I'm also trying to get the resolution of the video stream and stretch the window if it comes with a different resolution.
I think that the video will be deformed because the two ratios are not equals (the 4:3 has a ratio of 1.33333 an the 16:9 has a ratio of 1.77778).
I usa a Poster element to show images and can apply the loadDisplayMode as "scaleToFit".
But, in the case of the video element, the Roku system will adapt the video to the screen ratio (in general is a 16:9). It will add one black bar on each side of the video so it will not be distorted.
In the video documentation (https://developer.roku.com/pt-br/docs/references/scenegraph/media-playback-nodes/video.md) there are 2 parameters in UI Fields, width and height.
width. float. 0.0. READ_WRITE. Sets the width of the video play window in pixels. If set to 0.0 (the default), the video play window is set to the width of the entire display screen.
height float 0.0. READ_WRITE Sets the height of the video play window in pixels. If set to 0.0 (the default), the video play window is set to the height of the entire display screen.
Maybe if you set these values to 0.0 they will scale to full width/height (with some cropping or distortion). This could be tested but I don't think it will work.