The problem with a stun baton like this is that you have to keep it on the guy for several seconds for it to do anything. You almost have to subdue him in order to keep it on him long enough for it to be effective. If you just touch 'em with it they will just take a step back, say "you fucker!", and then pull a gun on you.
No problem being in Cali really. All it takes is a little $$$ and the right connection to get a permit to carry concealed. If you really want to get one it's not that big of a deal. If you ask around or read shit online people make it sound like it's impossible, but it's not.
If you have to be in the hood at night you can also just open carry and keep a loaded mag in your pocket. Perfectly legal. (no more than a 10 round mag of course!)
Of course, these types of situations are easily avoided 99.9% of the time by not doing stupid shit like stopping in the hood at night and getting out of your car when 6 dudes want to kick your ass. I mean, this shit doesn't go down in broad daylight except in places no sane person would live (Oakland, etc)
The dude in the video had balls but if those "thugs" had any fighting skills whatsoever they would have subdued him in a matter of seconds and then done anything they wanted to him. He's lucky.