I think he's referring to this sample (https://doc.qt.io/qt-5/qtdoc-demos-photoviewer-example.html https://doc.qt.io/qt-5/qtdoc-demos-photoviewer-example.html)

I think he's referring to this sample (https://doc.qt.io/qt-5/qtdoc-demos-photoviewer-example.html https://doc.qt.io/qt-5/qtdoc-demos-photoviewer-example.html) - replace Image by VideoPlayer, tweak the ui, make some menus, add a few interactions and you're good to go from what is visible on your screenshots - were I still a freelancer I would maybe have quoted two weeks for that ?