I just found this other project that maybe could help:
https://github.com/itschasa/speedrr
It doesn't do exactly what you're looking for but you can set it to slow down your overall torrent upload speed whenever you're streaming from your media server.
Edit: unless the issue is CPU usage? But my guess is that it's a bandwidth issue to enable uploading on all of your torrents.
Shocked nobody mentioned The Shawshank Redemption yet. Box office flop, they had to re-release it back to theaters after it got nominated for 7 Oscars and it only really took off with home video.