Great observation. He plays it like it's Rachmaninov

The Bunte Blätter Op. 99 and the Albumblätter Op. 124 were both published in the late 1850s. They were initially intended to be published as one collection of 34 pieces titled "Spreu", but Schumann chose to divide this work into two smaller sets upon his publisher's protest. Both of these sets are comprised of pieces Schumann had written earlier in his life but had hitherto refrained from publishing. Some of these pieces were rejected from earlier compositions. To give some examples: the third Albumblätter was originally intended to be part of the Carnaval Op. 9, and it shares the same A♭ C B motif as some of the pieces in there; the scherzo was taken from sketches for an unfinished symphony and was the only movement completed from it (albeit unorchestrated); and the concluding Geschwindmarsch was originally written for inclusion in Marches Op. 76. Others may have had personal connections to Schumann; for instance, Schumann wrote the first Stücklein in late 1838 as a Christmas gift to his wife Clara. These pieces (and the ones in Op. 124) have a storied history and one which gives insight to Schumann's compositional career.

I wonder if that was a discarded piece from Carnaval.

Composer: Robert Schumann Performer: Youri Egorov

I can play Eb and Gb in the next octave just fine. However, I assume you meant C and Gb. The answer is, either have big hands, thinner keys, or just do a quick arpeggiation.

I can see someone skipping the Cb in the right hand entirely because you are already playing a Cb octave in the left hand. People also do something similar with the second variation of the Symphonic etudes which also has some less-than-reasonable stretches to the melody.

By arpeggiating it, a "nachschlagen" (afternote) was accepted in that period, or just skipping that intermediate note.