Mannix Is Held at Gunpoint by John Ritter at the Brady Bunch House
The set of The Brady Bunch was used for several episodes of Mannix. Both series were produced by Paramount Television and filmed at Paramount Studios. However, they aired on different television networks; Mannix was on CBS, and The Brady Bunch was on ABC.
The clip of The Brady Bunch is from the episode Vote for Brady (Episode 11 of season one). It aired on December 12, 1969. There were 117 episodes of The Brady Bunch, which aired from 1969 to 1974.
The clip of Mannix is from the episode Hardball (Episode 24 of season eight). It's also the series finale. It aired on April 13, 1975. There were 194 episodes of Mannix, which aired from 1967 to 1975.