Honestly, despite not being a writer, I find this video pretty motivating and useful. She talks about general writing things form her own experiences, but her viewpoint on writing dark stuff.
Anyways! Here is a mix of other videos I found helpful or inspiring.
This guy's playlist on writing thing.
Dead channel, but has some useful videos on cinematography. (Pretty much for horror, but they could translate to other genres.)
These folks are webcomic creators, and make some helpful videos about webcomic creation.
Another playlist on cinematography.
A channel dedicated to life drawing, tutorials, artist self-care and general art talks.
Finally for hella good inspiration (imo) I highly suggest HUMAN's Musics - A film by Yann Arthus-Bertrand, a visual movie showing people living their daily lives in different culures, set to gorgeous music.
I'd suggest checking out the whole channel, because it's pretty cool.