Maybe better than nothing (because they do drop some tidbits), and certainly entertaining. But a bit like doing a research paper with only an encyclopedia as a reference, if you know what I mean.
They are probably more interesting and useful for product related videos (eg demos) to be honest. The information density in most vids (not just theirs) is so low it would take an eternity for a newb to get a worthwhile amount of useful info – you'd spend a *long time*
not picking up fundamentals, knowing just enough to be dangerous.

"I can pick up a screw driver, so now I can build a house!"
No offense to anyone who goes unnamed (about to name names), but if I were a newb I would want to consume Martin Moe, Delbeek & Sprung, Tullock, Fosse & Nilsen, Baensch, Fenner, Borneman, Spotte (and maybe LOTS of others) with copious amounts of Michaels, Burgess, etc. for the livestock profiles!!!! I'd also read every back issue of TFH and FAMA back into the 1960's (including all the ads!!), as well as any other regular hobby magazine. Hopefully that's all online somewhere these days...seems like a lot of it is. Lots of old books are still in circulation, but a lot seem to have made it online as well, check (eg) openlibrary and archive.org.
Outside of the books, magazines and authors I mentioned, for online I'm actually thinking more like *everything* on the Advanced Aquarist archive and Reefkeeping.com (some of which is also here on R2R along with RHF, Dana, etc) with time also spent over on Google Scholar to go deep into references from time to time.
Mostly reading! LOTS, AND LOTS OF READING.
Online (ie videos, forums, etc) is (obviously) a great place to get answers to the questions that reading will give you though!
Such as: "Who the heck are 'Delbeek & Sprung'???"
("expert" HINT: You want all three volumes. Volume three is like an equipment catalog/setup guide where one and two are filled with
fundamentals. It may come as no surprise that all three volumes go together really well, with volume three resting squarely on the support from one and two. Their lopsided recommendation for Volume 3 also illustrates why they aren't best used as a primary resource. I take them as intending to be more entertaining vs educational anyway....a bit like old school "infomercials".)