Oscar buzz and all the positive chatter of critics were not enough to put Ben Affleck’s “Argo” at the top of the weekend box office. The political thriller directed by (and starring) Affleck drew large crowds — and earned $20.1 million in the process — but still finished behind ‘‘Taken 2,’’ a sequel starring Liam Neeson that raked in $22.5 million in its second weekend. Ethan Hawke’s fright flick ‘‘Sinister,’’ about a true-crime writer caught up in supernatural horror, debuted at No. 3 with $18.3 million, and the made-in-Massachusetts movie “Here Comes the Boom,’’ starring Kevin James as a teacher who moonlights as a mixed martial arts fighter, opened poorly with $12 million. Despite finishing behind “Taken 2,” “Argo” is expected to gain momentum among moviegoers. ‘‘This is a really good indication of how quickly word of mouth can spread,’’ Dan Fellman, head of distribution at Warner Bros, told the Associated Press. ‘‘The critical acclaim in this case is going to translate into commercial success.’’ According to The Hollywood Reporter, ‘‘Argo,’’ which cost $44 million to make, was seen by a mostly older audience — 93 percent of the crowd was over 25, and 52 percent over 50 — but the studio is hopeful the demographic will expand as people talk it up. “Good movies rise to the occasion. Both ‘The Town’ and ‘Gran Torino’ played older” before being seen by all ages groups, said Fellman. “Argo” is based on the true story of the rescue of six Americans hiding at the Canadian Embassy during the 1979 Iran hostage crisis. In addition to Affleck, the movie stars Bryan Cranston, Alan Arkin, and John Goodman.