The sign in this video tells you whether the two seats below it are reserved or not.
What's wrong with the sign?
Well, this particular video is 14 seconds long, and during that time you can tell that the seats are not reserved for a total of about 5 seconds. At other times, if you glance up at the sign you might see nothing, just a blank screen; you might see some partial information; or even worse for about 1 or 2 seconds if you look up you'll see "reserved", i.e. the opposite of the truth!
The text of the message (the top line, at least) is "13. This seat is not reserved". If they had written it as "13. not reserved", or even better, "13. available" then the text wouldn't need to scroll, and the message would be there 100% of the time, rather than a rubbishy 36% of the time.