I am a bit confused about the pronunciation of number 7 in native Korean number. As in the video here (at 27:47), the Korean teacher pronounced it as 일 리 겁. Could anyone confirm if this is correct or am I mishearing it?
In this video, the teacher is trying to say the words slowly. 일곱 is an awkward word to say slowly, as it moves from one consonant to another.
I think the '리' you are hearing is just a small 'artefact' of moving from the ㄹ to the ㄱ while keeping the sound voiced all the way through. You're not imagining it, but it's not significant either. Try to hear it as just two syllables: '일 - 겁'.