Originally Posted by
virtuo
If they look fine before you upload them, then it's probably YouTube putting in a low quality "placeholder" video before it gets processed by their systems (guess they must be getting busy for some reason).
I'd give it a few hours and try again.
This is from personal experience (albeit a few years ago now) of uploading videos to a previous employer's corporate channel, getting dragged backwards over the coals for the shoddy quality only for the quality issues to magically resolve themselves when YT got through the queue and processed them properly.