blackpenredpen (math): https://www.youtube.com/user/blackpenredpen

mathologer (math, rubix cubes): https://www.youtube.com/channel/UC1_uAIS3r8Vu6JjXWvastJg

Welch Labs (math): https://www.youtube.com/channel/UConVfxXodg78Tzh5nNu85Ew

Physics Girl (physics): https://www.youtube.com/channel/UC7DdEm33SyaTDtWYGO2CwdA

minutephysics (physics): https://www.youtube.com/user/minutephysics

Khan Academy (math, science, etc.): https://www.youtube.com/user/khanacademy

Bob Ross (painting): https://www.youtube.com/channel/UCxcnsr1R5Ge_fbTu5ajt8DQ

The Virtual Linguistics Camps (linguistics & phonology): https://www.youtube.com/channel/UCaMpov1PPVXGcKYgwHjXB3g

NativLang (languages & language history): https://www.youtube.com/user/NativLang

Dr Jackson Crawford (old norse, scandinavian languages, old english): https://www.youtube.com/channel/UCXCxNFxw6iq-Mh4uIjYvufg