@GArthurBrown That's more comparable to I went to him by bus than to the OP's sentences.

The Q is about the use of the definite article. Your suggestion is that that is somehow related to "the content of the television" being used without the article. This seems unlikely. Just as "I heard his song on the radio" not "I heard his song on radio."

@GArthurBrown Maybe my answer wasn't clear enough for you? Just in case, I have emboldened can/can't see in the last paragraph. As for "on the radio", you can't see the content of the radio, so you'd have to refer to the physical radio, which I think requires using the definite article.

"I think the reason" suggests that this explanation is wholly invented.

@JeffreyCarney Yes, it is. (And that's because there's no established explanation for this phenomenon that I know of.) So any criticism is welcome.

So you're saying it's the visual aspect? That's even less plausible. "I listened to his voice on CD/tape/record." Right now you have a blind guess posted as to why this happens. Let's remove the explanation until we've established a better rationale.

@GArthurBrown You're comparing oranges and apples. CD/tape/record in your example is being used as a material noun, which can be easier to use without any determiner than a non-material noun such as telephone and television. Thus, the lack of the definite article in your example is due to CD/tape/record being a material noun than anything else. Moreover, there are few grammar rules that don't have exceptions. That's especially the case when the rule is about article usage. So before you talk about removing the explanation, please come up with a better rationale or any rationale, if you can.

@Jk2 "I saw him in the photograph. I saw him in the film." Feel free to continue to attract downvotes to your baseless answer.

@GArthurBrown "The" in your latest examples is entirely different. It refers to a specific "photograph" or "film", whereas "the" in the OP's examples does not refer to a specific "telephone" or "television". I think you're running out of counterexamples.

You "can see" movies, and movies can refer to either actual films or the place where one goes to view them. "I'm going to the movies. I saw him in movies. I saw him in the movie/s" all are things people say.

@tubedogg In "I'm going to the movies", "movies" refers to the place where movies are shown, not the actual films (i.e., the content). Note here that "the" does NOT specify which movie theatre you're going to. In "I saw him in movies", "movies" refers to the content, not the place. In "I saw him in the movie(s)", "the" specifies the movie(s) you saw him in. So your examples can be analyzed the same way as I have analyzed "(the) television".

@JK2 But your argument is that "the television" refers to the device, not the content, whereas "the movie/s" refers to content, not the place (device and place are basically synonymous in this case). Therefore, you're saying "the movie/s" has the opposite of the generally-used interpretation of "the television," despite the fact they're both visual mediums and you were using that as your distinguishing characteristic.

@tubedogg You're erroneously assuming that the words 'television' and 'movie' are "both visual mediums". Please note that the word 'television' originally referred to the device, not the medium, and that the word 'movie' originally referred to the medium, not the place. And that's precisely why "the movie(s)" can refer to one or more specific movie(s) as content whereas "the television(s)" can hardly refer to one or more specific TV program(s) as content.

@JK2 Actually, the word "television" originally referred to what was then a theoretical system of transmitting images over wires, not a physical device, in 1907. In 1927, it began to be used to refer to the medium itself, while it was not used to refer to the physical device until 1941. So your comment is demonstrably incorrect, which casts significant doubt over what was already the complete conjecture making up your answer.

@tubedogg Is that the best you can do after over a month? Unfortunately for you, neither a "system" nor a "device" isn't a medium. So, a month of your research doesn't change the fact that the word "television" originally didn't refer to a medium (in 1907), whereas the word "movie" did. You need to do better than that.

@JK2 The word television originally referred to a theoretical system, not a device, which makes your previous comment wrong. The fact you claimed the original meaning of the word to be something that it wasn't until nearly 40 years after the word was coined (meanwhile coming into common usage as the exact thing you claim it didn't mean) means there is no point in continuing this conversation, because you are quite literally making this whole thing up as you go. Good luck with your entirely bogus answer.

@tubedogg The reason it was initially coined to refer to a "theoretical" system was because at the time of coining the term we hadn't invented the system yet. Theoretical or not, the term referred to a "system", which is a concrete thing as opposed to "movie", which initially referred to a moving picture, a medium as opposed to a system or a device. The difference between a system and a device is subtle in comparison with the one between a system/device and a medium. If you haven't figure that out yet, you're helpless. So yes, please stop this nonsense.