I don't know how to put hyperlinks (or "hippolinks") into an answer, but, if you google "television" and "hippopotamus", you will find that the 8th suggestion leads to Richard Herring's blog. From this, it seems that the question may have been incorrect, i.e. there may be nothing that connects these words, if this is indeed the original source of the question. (He asked the question on November 1st.)The suggestion that they can both be abbreviated to their first two syllables does not work - rhinoceros is another, and I'm sure there must be more.