Huh? Television is AM, so I agree that the information content is in the sidebands. First off what is interstellar scintillation, and second how can it demodulate a signal?
I did not say that well. Here is a better response: :-)
Electromagnetic waves as they propagate though the interstellar media suffer frequency-selective fading. The resulting corrupted signal is said to undergo scintillation effects. The higher the modulation bandwidth the worse the effect.
Thus all that remains detectable is the carrier itself. Using the term "strips" was a bad analogy.
Here also is a great series of slides on the subject.
A six dollar word for twinkle as in "scintilate scintilate minute stellar body."