Well, first a good RMA would have taught you to be a respectful, honorable person; not some woman bashing, chest thumping "I can take on 8 guys because I have a successful MMA record" douche like the guy in the video. So, yeah, like you said, it would teach you the legal and moral reasons not to be a wanker in the first place.
Second, it would have taught you to effectively control distance and keep yourself protected at all times (I find it quite amusing that while in the ring sport fighters tend to do this at all times, yet when it comes to real world violence they often fail miserably at it); so no "getting up in the other guy's face and jawing at him". If I was going to get that close to someone I would only be doing it to get in range to ambush them, not waste my breath telling them how "tough" I was (in fact I'd rather them underestimate me so that it comes as even more of a surprise to them when I am on top of them savagely beating them).
Third, a good RMA would have taught you that in such situations (multiples/weapons), that the last thing you want to do is engage them on even ground unarmed. There was no attempt to use an encumbrance (looked like they were in a convenience store, so you've got shelves, probably a back/staff door, and the front counter which you could have put between you and your opponents to decrease their access to you or at least slow their assault), an equalizer/force multiplier (again, you're in a convenience store, You've got beer/soda cans/bottles that you can hurl at people heads or use as impact or even edged weapons, you've probably got lighters and spray oil cans that you could use as a makeshift blowtorch, there might have been a firearm behind the counter that you could have accessed, if they sell hot sauce you could smash a bottle on someone's face or even just open it and fling it in people's faces to temporarily blind them, they probably sell coffee which you could use the pots to smash over people's heads or just again throw in people's faces to burn/blind them, etc...), there was no attempt to "cluster" the opponents (angle yourself so you only have to fight 1-2 at a time/don't get surrounded), or heck, just get the heck out of Dodge.
In short, he was thinking like an MMA fighter and not like a RMA fighter and as a result got his butt kicked.