Decrease the sharpness on an oversharped video

That pattern in the curtains is going to generate moray patterns when the video is compressed. I'd soften that quite a bit. I might even add some camera lens blur and do some roto to give the shot a little artificial depth of field. I don't have time to put together a sample comp but I am pretty sure that those lace curtains are going to cause a lot of problems. I would have moved the camera or reduced the depth of field significantly.

In the future, please embed your screenshots. It makes things a lot easier to see.

What other sources? Did you preview your render in a media player like Quicktime or Windows Media Player?

YouTube and Vimeo re-compress your video. If you do not render to their specifications the compression is done with a sledgehammer and it always looks terrible. If all you have is the original render you have to degrade the edges the best you can with the tools available in AE. The workflow depends entirely on the image. There is no one-click magic solution. We need to see a screenshot to even come close to any meaningful suggestions.