Left to their own devices my kids would watch all day people playing Minecraft/Roblox or YouTubers doing questionable channels.
I'm not too keen on that and I already limit a lot of what they can watch.
I am so close to banning YouTube in general but I know it also has good channels. Do you have any favourite channel for primary school kids?
None.
Numberblocks, SciShow Kids and TED-Ed
Don't let them watch YouTube/TV on their own for hours on end. Instead, set a dedicated daily slot and be with them for answering questions, providing perspective… and most importantly having fun with your kids.
I second the recommendation of https://www.youtube.com/@Numberblocks/ It's fun and has more math than what you may expect.
Also https://www.youtube.com/@TheFixiesOfficial They are cartoons, but in the middle of the story there are technical explanations that are more accurate than in the usual cartoons.