Mark The Shark said:
I am not 100 per cent certain about this, but I have read (I haven't seen ET in 20 years) that the "Sesame Street" clips shown in that movie are from one or both of the two "Star Wars" episodes (#1316 and #1364). There is even a "conspiracy theory" of sorts which I read on the internet somewhere claiming that George Lucas *owns* both of those specific episodes as a condition of licensing C3PO and R2D2 to appear in them, and that use of clips in Speilberg's "ET" is no coincidence. But I think that's nonsense.
I think I get it. The Big Bird audio about something coming from "outer space" did appear at the beginning of the first "Star Wars" episode, when the Bird so far was the first to notice that the Droids had landed behind the fence. It's been some time, but I think on ET, the audio followed was David: "Big Bird, what have you been reading?"
The visual part of what was being watched ("Ladies and gentleman/and monsters", etc.) was indeed an early skit which took place on the street but was repeated as an "insert" skit. I even recall it appearing in the mid-80's, of all times.
Somehow I don't think CTW gave an entire episode of Sesame Street for the E.T. movie, but rather, sent a small number of clips needed for the scene - Two "B" cartoons and one Big Bird scene.