Context: a mangaka is talking about the story of the manga she draws and its writer.
山口先生の執筆作業を中継で観たいです!
I am not sure what this sentence means, in particular 中継で観たい.
Does she want the manga to be broadcasted on TV?
(I don't know whose word it is, but it's ok.)
It says 執筆作業を観たい. It's saying the speaker wants to see the writer working on her (his?) work.
Now, I believe it doesn't really matter what 中継 is. Do we think this is the occasion when we matter how the picture has been brought to us? 中継 alone, we can't really tell what it's saying. Maybe it's a jargon used in the broadcasting industry, but fortunately we don't really need to know what that is here.
But at least we can tell that the speaker is saying s/he wants to see 山口先生 working on her/his work through some kind of media. Maybe implying the speaker can't ask for staying at the room where 山口先生 is working.
観たい is viewing
観たい is "want to watch", no?