Harpo Marx published his wonderful autobiography, Harpo Speaks, and made the talk show rounds promoting it. (Take a moment to consider the irony of Harpo appearing on a talk show.) One of the shows he appeared on was The Groucho Show (a later incarnation of You Bet Your Life), in a very brief but very sweet public reunion of Harpo and his younger brother.
In the post-Marx Brothers portion of his career, Groucho was generally resistant to performing alongside his brothers. They were still personally close, but professionally, Groucho felt (not without justification) that the Marx Brothers were finished. They had made the last real Marx Brothers movie (the uneven A Night in Casablanca) in 1946. The regrettable Love Happy, three years later, was really a Harpo movie, with Chico in a supporting role, and Groucho in a series of cameos. In 1961, Groucho made a brief appearance at the end of "The Incredible Jewel Robbery," a Harpo/Chico featurette broadcast on General Electric Theater (information and video here), and the same year, the three brothers filmed an unfinished and unreleased television pilot called Deputy Seraph. And that was all.
Therefore, we should all be grateful to the YouTube user thescribefiles, for making these precious Groucho and Harpo moments available to all of us.