I have watched that movie too.
Robert Redford had a stunt double for most of the skiing. And the double is a local man from Wengen, Stefan Zürcher. And that is an interesting figure. As youngster he went to the US and taught skiing in Vail. There he got in contact with some Hollywood producers, that needed someone to teach actors to ski, and if necessary stand in for them.
He is it who suggested the Schilthorn as location for "In Her Majesty's Secret Service". He was also Lazenby's stunt double in the ski chase when they escape from "Piz Gloria". Using Schilthorn as a film location actually saved the cable car company from financial ruin. Without it, it would never have been completed. Zürcher would also double for Roger Moore in the ski chase at the beginning of "The Spy Who Loved Me".
Some of "The Downhill Racer" was filmed in Wengen. The Lauberhorn race sequences were filmed on the actual Lauberhorn race course, but most of the village scenes were filmed in Austria. There is however one scene that is quite funny if you know the local geography. Redford comes out of the old Männlichen Cable Car station in Wengen, gets in to a sportscar with his love interest and immediately drives off. In the next scene they are driving somewhere in Austria. Which is of course impossible as Wengen has no road access :-)
Zürcher still lives in Wengen. He has a company that does location scouting for movies, but has recently had some health issues, so I guess he is now mostly enjoying his retirement.