There is some stuff but I wouldn't recommend trusting YouTube all that much for concrete information about Build; it's a different engine from Doom that is wired in a dynamic way that lends itself to linear video tutorials a lot less (instead being more suitable for text references you can go back to, in which case you could use the Infosuite
https://infosuite.duke4.net and the EDuke32 wiki). There also is a
lot of disinformation on there from YouTubers who think claiming the Build engine is their ticket to going viral but in reality they know zero about it. The amount of accurate information is exceptional and tends to be more or less lifted from the Infosuite and/or EDuke wiki anyway.
One channel I'd recommend checking out is Nacho/TLOD's weekly streams:
https://www.youtube....helegendofdevon they are to me the most fitting format to present the engine as they are half user map playthroughs where the levels get thoroughly scrutinized (also in the editor), and half mapping streams that directly show the trial and error process.