This video is actually quite old by now. So, it's not really of much importance.
But anyway, there's a glitch in SFA3 that causes a character to go into an invulnerability state if: You air recover and then air block in the corner, then you can land and perform an action and that action will be invulnerable. It's really quite obscure, and it's only triggered by that condition AFAIK (airblocking after air-teching in the corner).
But since the properties of this glitch cause the entire move to be invulnerable you can retain the invulnerability state by bypassing neutral states. Exactly like how you use crouch canceling and walk-canceling to bypass neutral states in order to prevent your opponent from air teching.
It really really is obscure though. It's not exactly something that would happen particularly often. But it's not something you can't plan for either, because if the opponent somehow manages to screw up a tech-trap then you're probably going to be airblocking in the corner, so then all you need to remember is that when you land you have the opportunity to abuse this.
At any rate, in the video you can see the player land and use a walk cancel to bypass neutral and retain invulnerability as Rolento, who gets thrown. Next part, Akuma also meets the condition and then uses rapid-fire jabs to keep himself out of neutral. In his case, Sakura can't even approach him in order to throw him due to the jabs, so her own invulnerability was necessary to grab him.
The next couple clips show another "glitch" regarding invulnerability. As said in my previous post about SFA3 there's specific characters whose air activations are fully invulnerable until attacking or landing: Adon, Akuma, Cammy, Charlie, Dhalsim, Guy, Juli, Juni, Rose, and Sakura.
The video shows Dhalsim using it. And then it shows Guy using a "Kattobi cancel", which is actually just a kara-cancel into VC activation. But since the move Guy kara cancels from is his down+toward+HK (backflip) move, it leaves him suspended indefinitely in the air. And since he's invulnerable until landing, well he's invulnerable indefinitely as well.
The air activation glitch isn't like the corner glitch in the sense that the corner one is only melee invulnerable and not throw invulnerable. The VC one, being throw invulnerable, makes Guy literally impossible to hit until round over.
While neither glitch would necessarily need to be banned in tournaments, usage of Guy's "kattobi" to run the clock would definitely be banned in tournaments.
Of course, these aren't the only glitches in the game.
There's a thread on SRK named All Dip Switch Settings Revealed!!! which shows all the dip switch toggles for all the SFA games on the SFAA disc. Just skimming through the list you can see all the glitches that existed in the arcade board that were either removed or modified in the console versions.
Fortunately though, with the SFAA disc you're able to select a preset that automatically sets all the dipswitch toggles so that it mirrors the 980904 arcade board perfectly, with the exception of star 2-15 which has to be unlit manually after selecting the preset.
In other words: selecting the 00/11/20ver preset then unfilling start 2-15 will make the SFA3 that's on SFAA run arcade-perfect.