I used mulch actually for the lavender. I use more sand and peat moss now since its a bit less prone to mold or killing off the more delicate cuttings. Sand is probably the best with a good dome to keep moisture in. Just make sure there is moister on the dome covering the tray and you will have roots.
What soil mixture did you use? Your info is helpful, but videos are a bit long.
I used mulch actually for the lavender. I use more sand and peat moss now since its a bit less prone to mold or killing off the more delicate cuttings. Sand is probably the best with a good dome to keep moisture in. Just make sure there is moister on the dome covering the tray and you will have roots.