Albert Einstein plays Mozart KV378 Sonata for Violin and Piano in B-flat? Probably an April Fool…although he did play violin, of course, just this recording probably ain’t him, he wasn’t apparently that good.
There are claims that it’s Carl Flesch, Szigeti, Kreisler, Menuhin. But, perhaps it’s Daniel Kurganov, the person who uploaded the video and he has simply artificially distressed a modern recording. Then someone reveals that the words: “Happy April Fools The Violinist Carl Flesch” are prominent in the Youtube description. Most likely: Carl Flesch with pianist Felix Dyck here.