Currently the rtmedia encoding service converts any video (that isn’t .mp4) to 320x240 regardless of the original aspect ratio. I personally think most video shot by the average user comes from their phone, most of which now shoot in 16:9 (unless using the front facing camera).
I would like to see original aspect ratios respected and retained. Upload in 4:3, output in 4:3. Upload in 16:9, output in 16:9.