I don't think I would call it a hugelkultur road, but here in the US, we call everything hugelkultur, so....
I think the way this was built, as seen in the video, it should work fine for use 10-20 times a year, but to me, seems that weekly, much less daily traffic would bust those 'punky' sticks into mush, and before too long you'd be dealing with gettting stuck again.
What would be an ideal fill material to fill in the spaces, cracks and give the grass and weeds a chance to set in some firming root structure? a clay mix? sand? gravel? I personally just don't know what would be best.
Compost maybe.