Hi folks,
I've been submitting footage to the agencies for some time now. Encoding or quality issues were never an issue.

Preparing video for stock is pretty straight forward anyway as I submit 30fps, .MOV, Photo-JPG (95%) and done.

However, preparing videos for Youtube are a total mystery to me. I've been researching settings, encoding tips and tutorials literally for years and my results are quite disappointing.

No matter whether I upload my original MOV files (for testing purposes) or mp4 (h.264) or ProRes files, the HD versions just look terrible (artifacting and just smudgy).

File size doesn't matter to me, I don't care if I have to upload GBs as long as I get nice crisp and clear footage. I know it works as thousands of Youtubers already figured it out... somehow.

Here a few settings that I already tried which did not lead to good looking HD playback:
https://support.google.com/youtube/answer/1722171?hl=en&ref_topic=2888648
https://support.google.com/youtube/answer/1679498?hl=en

I've tried rendering my files with Adobe After Effects, Adobe Media Encoder and using Quicktime Player Pro. All files look perfectly fine locally but once they are on Youtube it's over.

Years ago (I think) Youtube mentioned that HD versions required longer processing times so the playback of the SD and HD files looked the same right after upload. No idea if this is still the case as HD options are available for playback right away.

I would greatly appreciate your feedback or tips how to improve the HD playback quality. 

I only upload half resolution so not sure if my experience applies to you. I do notice that the first few days the playback does not always look OK. You can, however, change the setting on playback video - the tool (nut) icon on the bottom right of the video to the highest quality (480p). After a week my footage look good even on big TV screen. Also to note that the quality of playback video is dependent of internet speed of the viewer computer.

Thanks asmai for responding. I can see that the HD versions may take some time (days) until Youtube prepared them properly so I will wait a bit and see if they improve.

I'm sitting on a 100Mbit internet connection defaulting HD playback and always switching to 1080p playback manually as well just to be sure.