■ Plurals in speech: the alternation between /ɪz/, /s/, and /z/
 i /ɪz/ after the sibilants /s/, /z/, /ʃ/, /ʒ/, /ʧ/, and /ʤ/
ii /s/after other voiceless consonants
iii /z/ after other voiced sounds (including all vowels)
Extract from The Cambridge Grammar of the English Language/Rodney Huddleston, Geoffrey K. Pullum
Page - 1585
George Galloway MP at 0:15 pronounced the sibilant suffix in the word difference(s) here as /Is/ while below it is /ɪz/.
It looks queer to me. But since I have no idea why it has been uttered in that way, I choose you as the final arbiter.
That's his accent. It's barely noticeable. By the way, he's Scottish.