Crime Pays, Botany Doesn't for sweary, amusing, but very informative stuff about nature and plants in particular. Always with lots of working class solidarity.
EVNautilus for submarine shenanigans and cool footage of rarely seen marine life, especially cute octopus.
LUXE37 hasn't uploaded in almost a decade but they made cool Japanese car chase movies with stop-motion, toy cars, and amazingly detailed models.
OgmiosZen does relaxed, zen-like commentary over his dashcam footage of having to drive around London for his job. Often amusing. The channel has grown a lot and now he's narrating other driving videos which I don't like as much.
People Make Games isn't specifically leftist or anything, but it's the only place I've found putting out actual investigative journalism into things like workers rights, bad industry practices, exploitative outsourcing to the 'developing world' and more in the video game industry. They also do some fun videos on more niche or elaborate non-video-game gaming like elaborate LARPs or tournaments of competitive Microsoft Excel Spreadsheet solving.
The Craft Beer Channel makes interesting videos and documentary series about beer - from ingredients growing to breweries to pubs - with lots of focus on history and the current actual people behind beer production.
YouSuckAtCooking makes slightly amusing little recipe videos with some willfully silly editing jokes, but without any pretension. Good for basic recipes, done in the most basic kitchen with very available ingredients. Also includes little songs and pets at the end of each video.
) mostly shorts based, some 20 min vids infrequently.
) shorts that soothe the soul mostly.