Tetras and Bettas do not mix. Not even black neons.
Just 'cause it's on youtube doesn't mean it'll work! haha there's SUCH bad stuff on there sometimes...
The reason is that there will be a lot of fin nipping. What I've seen happen is that everything goes swimmingly (pun intended

) for a while and then one day you'll wake up and turn on the light and the betta will have had his tail ripped to shreds. Not fun. So maybe those people just haven't woken up to that one sad day yet... I've seen it happen several times now with different members though. I wouldn't risk it.
It's just better that they be on their own or with bottom feeders. Apple snails, cories, or Otos (but otos need super established tanks before you put them in because they're fragile.) Personally, I think cories are the best little fish. (Other than bettas, of course!) Get some of them and your betta and you'll be set! They do this cute dog pile thing where they all pile on top of each other. Very cute, if you ask me!
Welcome to Fishlore, by the way!
