on my Apple TV I often fast forward movies wenn the credits begin, because there are often some “hidden” parts at the end of the credit or within.
If I fast foreward a movie to it’s very end, than the playback stops and Infuse returns to the selection area. But the movie is not marked as watched properly in this case. The progress bar (which I still don’t like) on the movie art remains, and the options show “mark as watched”.
If you start the movie again, Infuse asks to start at position “x:xx:xx”, which is the end of the movie, the last timestamp in the file.
this also happens for TV show episodes, of course.