It's the Minisuka.tv video dvd25_mayumi-y01, released 2016-12-08. It was shot concurrently with her most recent IV, BMAY-009/DMAY-009 「そこはダメ」, which was just released a few days ago on 2016-12-20. If you Google the exact title from the screenshot:
山中真由美次回作DVD「そこはダメ」乳首ポロリハプニング!?セクシービデオ
the...