It’s an age old issue, those (free) platforms will re-encode all your uploads to bitrates as low as possible to save bandwidth.
You can also check previous discussion here:
Hi everyone!
I’m completely new to TouchDesigner and I’ve been trying to upload my TD vids to Youtube. I’m using the non-commercial version of TD and while the render on my computer is absolutely perfect, the quality on Youtube (and Vimeo) is really bad. I’ve tried several different settings, but nothing seems to work. I’ve seen dozen of HD videos from TouchDesigner artists on Youtube and Vimeo, so I know it’s possible, but I just can’t figure out how it’s done. So far, I’ve exported the projec…
Also see compression guidelines from Vimeo here:
https://vimeo.com/help/compression