I see what you mean, but this method is quite similar to the usual practice :
- opening of MX Player app
- launching of the video (from the "play" bouton that you mentioned, or by clicking the video name in the files list)
The widget allows to resume the video with only one action, directly from the homescreen.
More over, the widget can provide informations about the current video (title/episode number, elapsed time,...).
Something like the Samsung Video widget here under :
Envoyé de mon SM-N9005 en utilisant Tapatalk