The above clip was taken from an interview given by Shaykh Abu-Ishaq al-Huwayni on the Egyptian satellite television station al-Hikma on 7 July 2011. Al-Huwayni here explains that whoever insults Muhammad, even if he later repents, must be killed.
Later in the interview, al-Huwayni went on to contrast this with the case of one who insults Allah. He said that insulting Allah of course makes one an infidel, which is agreed to by all Islamic scholars, yet the one who insults Allah is not killed--he is merely called to repentance. This is because even if the whole world insults Allah, it does not matter to him--it does not hurt him.
After recounting a hadith regarding Muhammad being mocked by poetry from the Quraysh, al-Huwayni explained that Muhammad "had complete authority to waive his right (to kill those who mocked him). But the ruler does not have the authority to waive the Prophet's right." Al-Huwayni reported that Muhammad could waive this right whenever he wanted, but after his death he retained this right, meaning no one could waive the right for him. That is why those who insult the Prophet now must be killed.
He then narrated another hadith in which Abu-Bakr, the first rightly-guided caliph of Islam, became furious with someone who had mocked him. Abu-Barza offered to kill this man for Abu-Bakr. Abu-Bakr explained, however, that this right (i.e. to kill the one who mocks the ruler) was not given to anyone after Muhammad; or in other words, only Muhammad had the right to kill those who mocked him.
He said all of this in the context of the current controversy in Egypt with the Christian businessman Naguib Sawiris, a billionaire and founder of the Free Egyptians Party. Late last month Sawiris tweeted a picture of Mickey Mouse wearing a Muslim beard and jilbab, and Minnie Mouse wearing a niqab, which was considered to be mocking Islam. Al-Huwayni did not say explicitly that Sawiris should be killed for mocking Islam, but did say that all of his companies should be boycotted, even if he only owns 10% share in the company.
Subtitled video above, transcript below:
Whoever insults the Prophet (PBUH), if he later comes and apologizes, and kisses the shoes (of the ruler), and says, “I want all Muslims, every one, to return and strike me with the soles of their feet”—does the ruler have the right to accept this?
I bring up this question, as it was asked of me. The answer is that it is not permissible for anyone to accept this. Then what do we do with him? We kill him! But he told you that he repented. We still kill him, even if he repents!