Another good question We haven’t laid out super specific guidelines yet but I’ll take a stab at some general, provisional ones:
Sharing specific stuff you think others on the forum would enjoy or learn from: great! Overtly promotional stuff like “buy this” or “please like and subscribe”, especially without context: not great.
If active members (like you!) want to share things you’ve made on YouTube, I think that’s fine so long as it doesn’t feel like it’s crowding out other discussion i.e. don’t only post links to your own stuff or be like that spammy person on Craigslist who posts the same thing 10 times in a row to maximize clicks ‘n’ views
In general we’ll give you the benefit of the doubt if we recognize you as someone who’s been here for a while and consistently participates, as opposed to someone who shows up out of nowhere and starts spewing links all over the place. I also think if you write a bit about why you’re sharing something, that’s always helpful in actually starting a conversation around that thing.
So far we’ve been pleasantly surprised with a distinct lack of forum spam. I believe any user can flag any post if you think something crosses a line, but so far we really haven’t had much of that sort of thing to moderate. Knock on wood!