OK so at low percents, ZSS's up air does not hit you up high enough to be out of range from a jump, but it does have enough hitstun to keep you from attacking with slower moves. He is fastfalling his Uair, then jumping and Uair again. ZSS's Uair is not actually safe on hit at low percents, meaning characters with fast moves like Mario's or yoshi's nair can hit hit ZSS before she gets out of the lag of doing the Uair. But assuming you were playing ZSS, and on For Glory, ZSS does not have any aerials that come out fast enough to get this off. Plus he was fastfalling away from you. a character able to interrupt her (like mario or yoshi) would have had to Fastfall as well to catch her. Also, For Glory Lag makes it even easuer to string the Uairs together because your timing of your airdodges is probably off by at least a few frames. What he was doing was not technically a combo at that percent, but Uair Uair Up B is a ZSS combo. He was just taking advantage of For Glory lag and ZSS's bad combo breaking options to land this string. Also, the Down smash to down B is a true combo. The knockback of the downsmash provides a perfect angle to land the down b, and there is tons of hitstun due to the multiplying effect that electricity has on hitstun (moves with electric effect do more hitstun, allowing for more followups.) it's all about going into the lab and figuring out how long a person is stunned for before they fly backwards from the knockback. That is all about getting the timing down based on percent. I am not sure about the lagless paralyzer landing. I have heard of it multiple times, and i do know that the sound of the paralyzer does not come out if you time it on the landing. i can't confirm if it actually cancels lag or not. Good Luck!
