 He has also contributed to films, such as "Muppet Treasure Island" and "The Hitchhiker's Guide to the Galaxy".Plaskitt appeared as Unstoffe in the four-part "Doctor Who" science-fiction serial "The Ribos Operation" in 1978.In British television advertisements, Plaskitt appeared as the character Malcolm, a young man suffering from a heavy cold, in a series of commercials for Vicks Sinex nasal spray from 1972 to 1981 and a one-off revival commercial in 1993.