I use Smartwebdisplay and the height and width settings are for the frame, not the content within.
Not sure if you can do the same but to get mine to display correctly, I set my DVR to quad camera view. I then moved the camera I wanted into position 1 and resized the frame to the height and width of that first camera, even though it is still receiving the stream for all 4. It still has to be slightly larger than I wanted but does the trick as the Iframe is sizing from the top left.
I don’t know of an Iframe viewer for MM that allows you to resize the contents but if anyone comes across one let me know please!