But אתה is the ms pronoun "you", not "he". And אותך is the direct object "you", not "him". So are you just using the example of "he" and "him" to demonstrate the difference in meaning between the two "you"s, because "he" and "him" are actually different words in English, whereas the pronoun "you" and the direct object "you" aren't?
The audio from the woman speaker in Hebrew is a barely audible whisper and there is no slow speech. Mah zeh? Why does the Hebrew course put audible stumbling blocks in front of those trying to gain an ear for Hebrew???! !! If there's only one take on the audio at least try to make it clear and distinct.
It's an issue, but the words are there with nikud in the companion course at Memrise, Duolingo Hebrew vocab with audio (just words & audio set up in groups according to the skills in Duolingo.
This is the course I started before Duolingo: http://www.memrise.com/course/1031737/hebrew-duolingo/
It's all the vocab used in Duolingo broken up the same way Duolingo does with audio. But no grammar. I'm on #35, I've found it very helpful to know the vocab before using it sentences.
otkha, (ot-KHA) = masculine form;
the tiny 'T' shape (the niqqud for 'ך') is called kamatz. It corresponds to the 'A' vowel sound that immediately follows the consonant ('KH', like the German 'CH' sound, in this case).
In contrast: otakh, (o-TAKH) = feminine form;
this is often shown with shva - two dots, one above the other, under the same letter (kaf soffit).