Im a bit unclear as to how you are doing this, so the image you are happy with in c4d? but final render looks bad ? you have no sound can you hear the sound in c4d i.e. did you get an audio file when you downloaded? If you did you can include this file in c4d and render with image and final result will have audio.
I only ever use c4d for audio reference, i would put my final render in another package ie after fx and or fcp what ever you have then i would add sound, then export for youtube, at specific youtube compression settings so that my image will look good on youtube. ?
Emmet