Crowds:

- https://youtube.com/channel/UCLXDNUOO3EQ80VmD9nQBHPg - Fouloscopie - he studies crowd behaviors (it's his research). Very funny and interesting.

Linguistics:

- https://youtube.com/channel/UCofQxJWd4qkqc7ZgaLkZfcw - Linguisticae - a fervant defensor of descriptivism, has a really good long video presenting the Academie française and its numerous faults

History (the two unmissable French channel on the topic):

- https://youtube.com/channel/UCKjDY4joMPcoRMmd-G1yz1Q - C'est une autre histoire - she has a PhD

- https://youtube.com/channel/UCP46_MXP_WG_auH88FnfS1A - Nota Bene

Critical thinking, avoiding fake news, reasoning biases:

- https://youtube.com/channel/UCMFcMhePnH4onVHt2-ItPZw - Hygiène Mentale

- https://youtube.com/channel/UCU0FhLr6fr7U9GOn6OiQHpQ - Officiel DEFAKATOR

- https://youtube.com/channel/UCNgudhx2s_ubmiA2L_2NMmg - Defakator Vite Fait - short versions of his long videos

- https://youtube.com/channel/UCAoUBng0Mfu0qn4lPimS6MA - G Milgram - handles stuff like QAnon, witches on TikTok, etc

(if you are really into the subject of critical thinking and zététique (the discipline where you try to check paranormal phenomenon with rigorous scientific method), I guess you can check out Richard Monvoisin's lessons at the Grenoble Alps University - https://skeptikon.fr/c/5f74ed4b-cc3c-4b33-a33d-06f49282ada5/... - quite comprehensive, not everybody likes his tone, Hygiène Mentale will probably sound more balanced to these people. I guess I'll need to check out the whole Peertube skeptikon instance)

Math:

- https://youtube.com/channel/UC0NCbj8CxzeCGIF6sODJ-7A - Science4All

- https://youtube.com/channel/UC4PasDd25MXqlXBogBw9CAg - Mickaël Launay

General science stuff:

- https://youtube.com/channel/UCaNlbnghtwlsGF-KzAFThqA - ScienceEtonnante - He has a PhD in the area of quantuum physics. A bit like Veritasium, but a bit less sensational

- https://youtube.com/channel/UCeR8BYZS7IHYjk_9Mh5JgkA - Scilabus - she also has a PhD, usually on random things of everyday life

- https://youtube.com/channel/UCaZRpfXzlHVchIJMpf-PVFw - Sci+ - her meta channel on vulgarisation

- https://youtube.com/channel/UC4Jrte_YtwWfANKNyzse5iA - Avides de recherche

- https://youtube.com/channel/UCcziTK2NKeWtWQ6kB5tmQ8Q - e-penser 2.0 - general science stuff. His videos from a few years ago are entertaining. He does not like putting his sources though

- https://youtube.com/channel/UCE_LWXcsdp7cWbo4DR4ZA-A - Science de comptoir - fun, with a lot of puns everywhere. I fail to focus on her videos unfortunately, I'll need to try harder.

- https://youtube.com/channel/UCZxLew-WXWm5dhRZBgEFl-Q - Le Vortex - ARTE - a vulgarisation series with many of these people on this list posing as roommates - really good, interesting, fun. You really need to check this out. I've been discovering a lot of those great channels thanks to this series.

Economics:

- https://youtube.com/channel/UCyJDHgrsUKuWLe05GvC2lng - Stupid Economics - economics stuff

- https://youtube.com/channel/UCynBu7PDfJsCXeCSqT1QUQw - Vous Avez Le Droit - legal stuff

Marketing:

- https://youtube.com/channel/UCAiy7bY8nTQCWrkSRh6Wu9w - Un Créatif - about marketing, mostly fun but he stopped recently

Astronomy:

- https://youtube.com/channel/UC5X4e8ScZI2AFd_vkjSoyoQ - AstronoGeek

- https://youtube.com/channel/UCS_7tplUgzJG4DhA16re5Yg - Balade Mentale, mostly philosophical for the few videos I've seen

Computer science:

- https://youtube.com/channel/UCYnvxJ-PKiGXo_tYXpWAC-w - Micode·Enquêtes - nice for people who are not strong in computers but curious. He infiltrated a network of scammers, his videos on this are quite interesting

Philosophy:

- https://youtube.com/channel/UCqA8H22FwgBVcF3GJpp0MQw - Monsieur Phi

Stuff I need to check out but seems promising:

- https://youtube.com/channel/UC9BnGZLT4iPaJtDOXYwQuHQ - Primum Non Nocere

- https://youtube.com/channel/UCV6uM3y-8TeO7JlCtcEN-Bg - ScienceClic

- https://youtube.com/channel/UC1EacOJoqsKaYxaDomTCTEQ - Le Réveilleur - the few videos on climate change I listened to are worth checking out

- https://youtube.com/channel/UCHGMBrXUzClgjEzBMei-Jdw - Le dessous des cartes - famous geography TV (ARTE) program - I've heard it was better in the past so maybe check out older videos first