Following my previous remark on the subject: on TV or in TV, I decided to translate this sentence by "in the TV". This was rejected. In this case, I am looking at was is IN a TV (the electronics). I, therefore believe that my answer should be accepted. what is IN THE television. Unless of course televísió is only used for the programming contents and not the appliance.
You're certainly not wrong grammatically speaking. However, it seems clear to me that the point of this example is to teach us that the inessive case can be used in the abstract sense for which we use 'on' in English, so I think it's more helpful to mark 'in the TV' as incorrect, in my opinion.