From those, the clip from SL is bit better, but still shows pixelation a bit. Not that much that it would really bother anyone. People watch for content over video quality.
And you do realize that recordings can't be compared as ShadowPlay has 60000kbps which is 10x more than SL? You can see that the difference is huge. with 60Mbps, the clip is clear. And I think it would remain clear even if you went through uploading it to YT adding YT compression to it.
I'm bit out of the game with streaming gaming content, so I don't know whether GPUs age will have effect of rendering quality when its 6000kbps. And can't really test it either.