While conventional plays are fascinating and complex pieces of art, it is easy to forget on viewing them that the word "theatre" has its roots in the verb "to behold".
True - θεασθαι "to behold". θέᾱτρον was "place for seeing, esp.for dramatic representation, theatre" (maybe related to zen.) And it certainly is easy to forget this, since most people probably didn't know it in the first place. And there's no reason why they should. Etymology is cool, of course, but knowledge of etymology is completely unnecessary for using a language. What's necessary is not what words used to mean, but what words mean now.
The author of this program is using etymology to make a point about art, not about language, so maybe it's unfair of me to use it as an example. But it's an opportunity to discuss something I have not discussed on this blog yet: the etymological fallacy. This is the belief that a word's etymology determines its meaning. We see it whenever someone claims that decimate should mean "destroy one tenth", or anxious should only mean "full of anxiety", or that unique should only mean "one of a kind". Or when someone claims that enormity should only mean "enormousness"... wait, no one claims that, but they should if they want to be consistent.
Sometimes it is claimed that an earlier meaning of a word is its literal or real meaning, but really all that can be said is that an earlier meaning is an earlier meaning. Word histories are endlessly fascinating, but for all practical purposes they are irrelevant. Those who say that the real meaning of decimate is "destroy one tenth" should destroy their calendars for mistakenly putting December as the tenth month. They should also correct everyone who uses nice to mean "pleasing" - every English speaker, in other words - when its "real" meaning is "ignorant".