I've never seen this demo'd and couldn't find any discussion about it being possible. So, here a video and some words.
This is an option select against backdashes and certain reversal options. If you opponent blocks or is hit, Zangief remains grounded and continues a combo or block string. if they back dash, Zangief will re-jump and instant air Ultra 2.
Some things to note, unlike a lot of other option selects, the frames you gain when the jump attack whiffs must be spent as economically as possible, otherwise the os will fail. By this I mean, the Ultra 2 input (in this case, from back to up-forward, held for a few frames) must happen late enough to allow Gief to re-jump but early enough so that, if the jump attack connects, the motion doesn't pre-buffer a running grab when you land (which will come out instead of the crouching short). So the actual input is...
j.HK, immediate 540 motion ending at up-forward (held), KKK, cr.LK... Exploit whichever option you ended up with (for Ultra 2, hold forward to catch the back dash. For a block, tick throw them for not back dashing).
Often you will have a huge window for error when option selecting with someone like Ryu but that is not the case here. This is even more true for the cr.LP variation @1:01. In this case you're exploiting the fact that a cr.LP can be chained well into it's active frames. So much so, that if you time it correctly and it whiffs, you can use those frames for an instant air Ultra2. The input for that variation is...
cr.LP, 540 motion ending at up-forward (held), KKK (this will either activate ultra or chain a st.LK), st.LK... At this point you can react to whichever option you got.
A. Showing the basic set-up vs backdashes, ex.chicken wing, ex.headstomp, ex.devilsreverse, ex.headbutt and ex.messiah kick.
B. Showing a corner only set-up from a cr.LP. If Yun blocks or is hit, you will remain on the ground and combo, if he backdashes you get instant air Ultra2. This is less practical and more difficult than the standard set-up.
C. A variation that leads directly into a tick > SPD. Without a block string. You can actually do whatever you like after the j.HK even after inputting the os. This is a safer option if you don't have the timing perfect as it will avoid the unintentional running grab/SPD.