All information on Humix is found in the guides available at support.ezoic.com - just search 'Humix' and you'll find guides that explain how the network works, how earnings are generated, and how to optimize.
There's no way to 'force' higher ePMV's necessarily, it's more related to where your videos on the network are displayed and what those sites traffic patterns look like.
The 'improving video revenue' you mentioned is simply related to bringing on higher paying advertisers for video content, but that doesn't mean every video would necessarily start seeing higher video revenue - again, because it's more dependent on factors like niche, topic, relevance, and traffic patterns.