sideburns, mustaches, the right clothes (thrift shops should handle this) and models who aren't the perfect buff look we see today. some cheesy motels will have that orange and brown late 70's furniture and carpets that will make any video look old. then you buy old style porn music and have the start of each video have guys use words like foxy

i'm sure you can find some kind of program to make video look vintage without shooting on film.