To help out, let me point you to the English phonology page on wikipedia: https://en.wikipedia.org/wiki/English_phonology . Specifically, look into the 'Voiced alveolar sibilant', the 'z' in English. That's the sound you're looking for, as it's the one used by Raph in the linked talk.
For completeness, the vowel is the dipthong 'aɪ', pronounced like the 'i' in the word 'price', discussed on the same wiki page.
Great resource, thanks a lot! I think this is really the stuff you can't learn in high school education and have to learn by yourself. There our teachers are native Germans as well and while they are probably better than the average second language English learner they can't be perfect either.
For completeness, the vowel is the dipthong 'aɪ', pronounced like the 'i' in the word 'price', discussed on the same wiki page.