Secondly, with a few exceptions most of these channels do not focus specifically upon the fantasy or speculative genres, and they're not even channels by writers. The majority of YouTube channels below are, I believe, informative, often entertaining and well worth the time of any fantasy writer. Also, this list is not meant to be exhaustive, but is merely made of channels I personally have found useful and interesting. The videos shown are only a sampling, and should not be considered representative of everything available at the individual channel.
featured on the channel. Still, I think this is one of the best sites for learning about European historical swordsmanship, other historical weapons, armor, etc. Though not as experienced as someone like Matt Easton (Skall often calls himself a beginner), there is still much to pick up here. For one thing, most viewers also are likely to be beginners, or only armchair swordsmen (waving my hand here), and it can help them to study the basics along with another beginner. But swords and training aren't all that appear on this channel. If you are interested, Skall sometimes has a firearms video or a more philosophical video or even a fun, entertaining video featuring a bit of role playing.
Nerdarchy: This channel focuses upon tabletop role playing games, usually Dungeons and Dragons, but quite often the information discussed can be of interest to fantasy fiction writers. The regular crew here are Ryan, Ted, Dave and Nate, but friends of theirs show up from time to time, as well. There are videos here of actual gameplay, so you can learn about tabletop RPGs if you're not in the know, but this channel tends to focus upon group conversations about aspects of the game, many of which can also be related to writing. Storytelling, character arcs, world building and more are common topics of conversation. As the gang often says, "for nerds, by nerds."
hickok45: Perhaps a little less useful to the fantasy writer, this channel focuses upon firearms of all sorts from history up to modern day. The emphasis is upon modern and semi-modern firearms, but occasionally there is a video about black powder weapons and the like. Still, to some extent or other the information here should be of interest and worth study for most fiction writers. Besides, the host, hickok45 (and sometimes his son, John), is pretty entertaining and offers plenty of hands-on knowledge and experience.