The contraction -- didn't -- was not accepted. Should it be? (He didn't speak enough.)
Could this also be [formal] you did not speak enough, or must is start - O nem... [+ accent on O]
It can be both. And the way to differentiate is context. When you are formally talking to somebody, who just gave a speech, it is obviously the formal you. And if you are talking about a third person, then that's that.
is elég a noun in this context? and that's why it has an accusative ending? could you also say nem elég beszélt or is that different/wrong? Thanks!