Today is the bicentennial of Richard Wagner's birth. The clip above, thanks to mitjanus, is of Siegfried's Funeral March from Götterdämmerung (Twilight of the Gods), the fourth and climactic opera in Wagner's Der Ring des Nibelungen, or as it's usually called in English, the "Ring Cycle." (Was it an influence on Tolkien? The author of The Lord of the Rings denied it, but as Alex Ross in The New Yorker argued, it almost certainly was.)
The performance is by the London Philharmonic Orchestra, directed by Klaus Tennstedt. The Sturm und Drang is momentarily broken at 5:50 when Tennstedt drops his baton.