Didn't mention explicitly Beethoven's influence on Reicha, but I'd say the sonata movement he played at the end of the video (Grande Sonata in C Major) is inhabiting the same sonic world created in the third movement of the Waldstein sonata. IMO, influence was stronger in the Reicha --> Beethoven direction, since he simply adopted many of the same lifelong concerns of Reicha's into his own work around the same time Reicha left Vienna, and becoming even more pronounced in his "3rd period", while Reicha continued steadfastly on his own path.
Could it be that the Hammerklavier fugue, marked "con alcune licenze" is a kind of rejoinder to Reicha's Op. 36, about which he is said to have remarked, "daß die Fuge keine Fuge mehr ist"? What about the fugue in the D Major cello sonata, with its displaced accents and unusual structure? Could it be a riff on the compound and irregular metres seen the same Op. 36? What about the overall structure of the Diabelli Variations (a long series of different perspectives on one idea, which could potentially go on forever--not counting the penultimate section and coda)? Essentially the same fundamental structure as L'art de varier (which deserves a similar stature in the piano repertoire). Possibly the final variation, no. 33, a minuet is a reference to no. 39 in Reicha's set: https://www.youtube.com/watch?v=ks1jAMN7XTw&index=40&list=OL...
Could it be that the Hammerklavier fugue, marked "con alcune licenze" is a kind of rejoinder to Reicha's Op. 36, about which he is said to have remarked, "daß die Fuge keine Fuge mehr ist"? What about the fugue in the D Major cello sonata, with its displaced accents and unusual structure? Could it be a riff on the compound and irregular metres seen the same Op. 36? What about the overall structure of the Diabelli Variations (a long series of different perspectives on one idea, which could potentially go on forever--not counting the penultimate section and coda)? Essentially the same fundamental structure as L'art de varier (which deserves a similar stature in the piano repertoire). Possibly the final variation, no. 33, a minuet is a reference to no. 39 in Reicha's set: https://www.youtube.com/watch?v=ks1jAMN7XTw&index=40&list=OL...