No MR champion complaining he got destroyed by an assassin who procced Lich Bane twice on him, ignited him, and got a FULL DAMAGE W on him. He had 5 kills as an Assassin and bought a damage item. You were 6/3 as an offmeta build (while still a level down btw) that bought an item that doesn't give you ANYTHING besides 20% CDR and barely over an NLR in AP in terms of combat stats.
Also, Fizz E doesn't do nearly as much damage as his W which was either rank 4 or rank 5 at this point depending on if he maxed it first or second.
Based on the clip you took (I will even assume rank 4 W for you):
116.6+93.3% AP from his W dot (you had the dot for 7 seconds)
20+110% AP from the two Qs (even if the second one was overkill he did get two on you)
132+100% AP from the 2 Lich Bane procs
180+120% AP from the W activation
160+30% AP from Electrocute
355 damage from Ignite.
This is all going against your 8 MR (34-18-8 from sorc and sudden impact with sudden impact having uptime for everything but the last 2 seconds of the dot and his last Q) meaning you only take 7.5% reduced damage from him bringing these numbers down to 562+419% AP (+355 from ignite). Assuming Fizz goes Dom+Resolve (its the more common one on probuilds and would make sense since Kaisa SHOULD bully him out of lane early) he gets 24 AP from runes (9+15 from a completed Chrysalis) and 115 AP from items bringing his AP to 139. This means to you he did a grand total of 1499 damage give or take like 20 damage either way due to rounding decimals throughout. Roughly 1500 magic/true damage. He auto'd you 6 times for 528 damage against your 59 armor (37% DR) meaning you also took 332 physical damage for a grand total of of about 1832 damage. You have 1317 health and ulted for 228 meaning you got overkilled by about 287 damage.
We could go with the circle jerk of "Fizz OP hurr durr" when the biggest mistake in this entire video is at 15 seconds where you E in instead of just being happy you got his ult down. You greeded for a kill and got punished. Fizz would have NEVER killed you if you didn't run into him. You're playing AP Kai'sa. A poke mage. Going for an EXTENDED all-in against a champion that can and WILL kill you because your champion simply does less damage than his unless they are stacking health is a stupid idea. It's either that or you dying with your barrier up which is another sign of complete greed, but hey what do I know. You played that perfectly and fizz is blatantly overpowered when you also made mistakes. /s even though I shouldn't have to type it.