Are there any tips or videos for people running on flats or downhill at a moderate pace?

It seems like running downhill, or running on flats at a moderate pace are particularly awkward to figure out form for. Downhill it feels like if I just ran a lot faster, it'd be easier, but that's not always an option (e.g. trail running downhill where a fall would be catastrophic).

On flat terrain whether trail or road it feels like there's kind of an "awkward" speed at which I start shuffling and then a bit faster than that feels "right", but then I get winded too quickly

I guess I could just sprint down hills and on flats and then walk up the hills