Passive Voice Sentence:

More concern was shown (by television viewers) over the Super Bowl than over the outbreak of an international conflict.

Is this correct for an Active Voice:
The Super Bowl had more concern over the outbreak of an international conflict.

The Super Bowl didn't have the concern. Who was concerned? What were they concerned about?

The television viewers were more concerned over the Super Bowl than over the outbreak of an international conflict.

Yay! That's right.

No, the rephrased sentence you provided is not correct for an active voice. Let me explain how to convert the given sentence from passive voice to active voice:

Original passive sentence: More concern was shown (by television viewers) over the Super Bowl than over the outbreak of an international conflict.

To transform it into an active voice sentence, you need to identify the subject and the action being performed. In the passive sentence, the subject is "More concern," and the action being performed is "was shown."

Now, to convert it into active voice, you need to make the subject the one performing the action (verb), and rearrange the sentence accordingly:

Active voice sentence: Television viewers showed more concern over the Super Bowl than over the outbreak of an international conflict.

In the active voice sentence, "television viewers" is now the subject that performs the action "showed." This rephrased sentence places the emphasis on the subject, which is typical of the active voice.