THE COUNTRY House on Film program at the National Gallery of Art continues Friday with Colin Clark's 1977 documentary on Kenneth Clark, An Edwardian Childhood. It will be shown with Henry Lewes' 1974 film on celebrated painters, The British Achievement, this afternoon (each film runs approximately one half hour). The weekend feature is Joseph Losey's 1971 drama The Go-Between (starring Julie Christie and Alan Bates), which will screen 2:30 Friday, 12:30 Saturday, and at 6 on Sunday. All programs are free, and will be presented in the auditorium of the gallery's East Building, Fourth and Constitution NW. For information, call 842-6272.

Friday marks the opening of the Biograph's 18-film Francois Truffaut retrospective. The opening bill (through Monday) is his first released short, Les Mistons (The Mischief Makers) and The 400 Blows, his feature debut. The festival, set to run through Christmas Eve, features all of Truffaut's films except for the five currently unavailable (Bed and Board, The Bride Wore Black, Mississippi Mermaid, Two English Girls and The Soft Skin). For a complete schedule: 333- 2696.

Thanks to the programmatic efforts of its annual National Video Festival (held in late September at The American Film Institute campus in Los Angeles), the AFI will tour an exciting package of Jean-Luc Godard's rarely screened video works around the country. The retrospective (composed entirely of area premieres) begins 8 p.m. Friday, right here at the AFI Theater, with Godard's hour-long "video scenario" of the 1982 film Passion (Scenario du Film Passion), double billed with his newest, autobiographical work, Soft and Hard. (The whole program runs two hours plus intermission; tickets are $4 members, $6 nonmembers.)

The serious stuff starts Saturday at noon in the AFI's third-floor screening room with the first part (nine hours' worth) of Six fois deux/Sur et sous la communication, a meditation on the role of television in family and society. Part two of that program, which runs three hours, screens noon Sunday. Tickets for the entire 12-hour program are $12 members, $15 non-members.

The retrospective concludes at Sunday at 4 with a screening of the six-hour France/tour/detour/deux/enfants, loosely based on a 19th-century primer called "The Tour of France by Two Children." This, too, concerns itself with TV's cultural impact -- in this case, on the way the media have altered the lives of children. The cost of that program is $8 members, $12 non-members.

If you're interested in seeing all 20 hours of Godard's seminal collaboration with Anne- Marie Mieville (who worked with him on Hail, Mary), you can purchase a series ticket for $20 (AFI members) or $30 (non-members). Most of this material is being presented in an English subtitled version for the first time, and since it still exists only on the European-standard videotape, this will be one of your few chances to view the material for quite a while. Don't worry -- intermissions will be provided. Seating is limited for the Saturday and Sunday programs; call 785-4601 for details.

The Smithsonian Institution Resident Associate Program will show two of Louise Brooks' best films this month. On Tuesday, you can see G.W. Pabst's Diary of a Lost Girl, and his legendary Pandora's Box will be shown November 26. Both will be presented in 16mm (with musical soundtracks) at 6 p.m. in the Hirshhorn Museum auditorium. Tickets are $4 for RAP members, $5.50 non-members, with series tickets offered at $7 and $10. 357-3030.

After a full weekend of Godard at the AFI, you'll be able to see the first 41/2-hour installment of Claude zmann's nine-hour Holocaust documentary Shoah (the Hebrew word for annihilation) starting Wednesday at the Key Theater in Georgetown. Showtimes are 1:15 and 7:15 daily, and tickets for the first part only are $10. The second installment will begin concurrent screenings on another screen at the same location on Sunday, November 24. This will cost another $10, for a combined ticket price of $20 for the entire film. Also, you'll have to plan on switching theaters between parts, as the entire film will never be shown in the same house. Intermissions will be provided during each program. This is an effective way to view this important movie event, and the Key Theater is to be congratulated for braving the economic storm to make it available.

Also on the Key's busy schedule, there's a tentative foreign film lineup running into early 1986: Upcoming titles include Krzysztof Zanussi's A Year of the Quiet Sun, Luc Besson's Subway, Percy Adlon's Sugarbaby and Akira Kurosawa's Ran. Call 965-4401 for details.

According to the Washington-based Motion Picture Information Service, the area's 10 top- grossing pictures for the week ending November 7 were, in descending order: A Nightmare on Elm Street 2: Freddy's Revenge (breaking wide on 21 screens); To Live and Die in L.A. (opening at 20 houses); Death Wish 3 (debuting on 17 screens); Jagged Edge (losing three houses to 15 in week five); Krush Groove (staying on 21 screens in its second week); Back to the Future (dropping three to 14 houses in its 18th week); Commando (moving from 24 to 22 screens in week five); Agnes of God (gaining another house, to nine, in its sixth week); After Hours (also adding a screen, to 10, in a month of release); and Re- Animator (holding steady at 12 houses in week two).

New Line Cinema took in 18 percent of the local gross with "Nightmare," and the two other independent releases of the week ("Death Wish" and "Re-Animator") helped spark a surge that resulted in a 20 percent increase over last week's figures. Looks like despite the good eather, people are starting to go back to first-run movies again (even if it is to see slasher fare).