when use acts_as_tenant, use belongs_to, or not? (yes say docs, no says Chris' video 11/2020)

Chris' helpful video says at 4:30 NOT to also use "belongs_to" in addition to "acts_as_tenant" because it "can cause problems".

However the Doc page gives this example with both:

Which is correct?

I've used the example with both acts_as_tenant and belongs_to for 10+ models in my project and haven't had any issues. 

Thanks, good to know. Given the vague "can cause problems" in his video, in the absence of any specifics from Chris, I'm using both as well.