i think if the recording quality is good that is attached to the video (whether is separately recorded and attached or not)
and u export the video in the right format that youtube likes/recommends, there is no compression or atleast the compression is very unnoticeable.
its not about exporting your video/audio in the highest quality at this point.
obv if u export something of higher quality then youtube compresses it down its gunna suck cuz their algo is generic and prolly sucks.
better to use the compression algo in your video software (which results in a much higher quality compression)
and export it to the right specs from the get go.
i'm not a video wizard by any means, but this is how i've come to understand it.