In Interstellar, after young Murph places the watch on the bookshelf in her bedroom, her father - in the same bedroom but from another dimension - moved the second hand and recorded data in a Morse-signal message on it. Many years later, the second hand still signals the message, grown-up Murph finds the watch and takes it with her to NASA and there she translates the message back into the data needed.
If we assume the watch had a long lasting battery, then I still see some problems with this plot:
- From what we know from the explanation in the movie itself is that the only thing capable to travel from them in the 4th or 5th dimension to present Earth is gravity. Gravity is a vertical force on Earth. It pulled dust from the air to the floor in a barcode-like pattern. So how can it adjust the horizontal position of the second hand of the watch? Like a magnet?
- And how is a multiple of those movements of the second hand recorded on the watch? How does it play the message for all these years, again and again. Not only in Murph's bedroom, but still at NASA too?
Normally I would answer this myself by saying that it is film, it is science fiction, everything is possible, and there is no need to question things we cannot explain. But this movie certainly has the intention of being truthful to science, to explain what is going on and this particular director has a reputation of telling stories that in one way or another always has plausible explanations for plot-hole-like aspects.