Here is an overview of youtube channels I'm following :
Knyght Errant : Superb research on 14th century armour (with a few sidesteps to earlier and later periods) debunking of Victorian reconstructions and common reenactor gear mistakes.
Lindybeige : Highly entertaining and enthusiastic, but mostly an opinion site. Lloyd is all over the place, he's a reenactor, wargamer, amateur historian and shares his insights, up to you to make you your mind on the subject.
Metatron : Interesting channel, covers mostly ancient and medieval as well as Japan. Reenactor, historian, some opinion pieces. Sometimes controversial, but worth checking out.
Schola Gladiatoria : HEMA pracitioner, medieval and later, including British Colonial. Focuses on HEMA techniques and various weapons. Cooperates with experts. Recommended.
Thegn Thrand : HEMA and practical testing. Tries to figure out how ancient weapons were used and how effective they are in combat.
Skallagrim : HEMA and practical testing, some historical stuff, gaming and firearms and well as knife reviews. Well worth checking out, offers a broad range of topics.
Wargaming – The Chieftain : US Army Major, tanker, historian for World of Tanks. Consults experts regularly, actually climbs in and out of tanks and gives detailed overviews of the features, good and bad points. Controversial, but eminently watchable in that he did an episode on paint drying …
Military History Visualized : Main focus is WWII, but touches on other periods. Debunks lots of preconceived notions, features extensive footnotes on screen.
TIK : History and Gaming, focus WWII and several military campaigns such as Market Garden and Stalingrad. Detailed research with footnotes.
Bloke on the Range : Englishman in Switzerland, talks firearms mainly.
Curious Droid : Aerospace and space exploration.
Isaac Arthur : Exploring concepts in Science, futurism and space expoloration
Extra Credits : Gaming channel, but has a very neat section on various historical figures and events.
Forgotten Weapons : Firearms, exploration of rare and not-so rare weapons, in depth looks and some testing.
Hickock 45 : Firearms, old guy who talks and shoots guns.
GI History Handbook : WWII US army manuals translated into nice videos.
Andy's Hobby Headquarters : Modelling tips and tricks.
Genessis Models : Modelling tips and tricks, also some wargaming.
Jackson Crawford : Professor of Ancient Norse at University Boulder Colorado.
Kathy Milatt : Railroad modelling by a woman !!!
Matthew Colville : D&D and RPG stuff
Minute Physics : Labels says all.
Moviebob : Movie reviews, gaming pop culture, strong opinions, but his Batman v Superman review is legendary and his 3-hour dissection of said film is a masterpiece.
Nerdarchy : D&D nerds
Nostalgia Nerd : 70s and 80s stuff, mostly computers.
Numberphile : Mathematics
Overly Sarcastic Productions : History, mythology, litterary technique, reviews, cute chibi cartoons.
Paul Harrell : Firearms
Shadiversity : HEMA, Machiculations and what weapon is best for an elf from down under (one of those people who occasionally go for the anyeurism, but still has interesting content)
Stalingrad Battle Data : Info from a French-Russian writer.
The Tank Museum : Tank Museum Bovington, talks by David Fletcher
The DM's Craft : Building your own dungeon stuff for D&D
Trekyards : Star Trek nerds
VBBSMYT : Schematic 3D models of early machineguns.
Zee Bashew : D&D stuff, animated.
Critical Role : D&D gaming session podcasts.