The Watch List feature on the Watch Recordings page creates a list of the recordings that would be most useful to watch in order to catch up on series and shows where you may have fallen behind. Choosing to watch and delete things from the top of this list will help you stay on top of things efficiently without having to examine the full recording.
Settings options can be found on the 5th page of TV Settings->Playback. There is some verbose info about the filtering and scoring when using
mythfrontend -v file.
This is turned on by default for now in order to encourage feedback. However, it may default to off for release if it is believed to be confusing to many users.