I don't know how vlc is able to do it; I guess it takes sort of time-stamp of a movie and puts it in cache or somewhere like that. This is the way it works in vlc -
a. You see a media file, say it consists of 1.5 hours, b. At some point, say after 15-30 minutes or whenever you feel, you stopped because you had some other work, a call came or anything which disrupted your viewing.
c. After some time you start the media file again. In vlc in the top-right corner it would give a small button saying continue from where you left off.
d. If you select that button/option, it starts playing the media file from where you last left off.
I have also seen using 2-3 media files in succession and even then it remembers the position.
Is it possible to have similar functionality in mpv? Is there a way this already works, or this would be a feature request I would need to make at mplayer github?