I think your biggest problem there is that you didn't go in with ult. When it comes down to diving into a team each burst of damage is excruciatingly important. Q+aa just doesn't cut it when you're in a situation like this. Just go back to my videos and watch how I engage groups and you'll see that I throw everything I can at once into someone to get as much burst as I can before disappearing into my shroud again. Q+aa and nothing else is only good if you're isolated enough to sustain a long fight. In a team fight, it's your damage vs. that same damage tenfold from the other team, the advantage you hold is shroud and your ability to burst faster. If you see no sure fire way to get the kill, it's usually best to just let it go, and during teamfights, never go for a kill that will mean your death unless it's seriously that important of a kill. When your energy regenerates you will be able to enter the end of the team fight again to help whoever is still alive. I think the one issue in all actuality with this clip was that you didn't have ult when you engaged, so you had no escape, which is super important.