YouTube's policy appears to ban videos that "promise users they will see something but instead directs them off site in order to view." As far as I can tell, mentioning that you have a Twitch channel should be fine, but creating a video called "my sick game livestreaming" whose content is a guy telling you to go somewhere else to watch your sick livestreaming might be seen as this type of spam. Honestly, that sounds pretty reasonable to me. Maybe I'm missing a story somewhere about them doing something worse?
> creating a video called "my sick game livestreaming" whose content is a guy telling you to go somewhere else to watch your sick livestreaming might be seen as this type of spam.
this happens a lot with many twitch streamers who also do youtube. I don't think it's banned under youtube.
I think this is the policy here: https://support.google.com/youtube/answer/2801973