It seems to me in viewing video from years back, that the younger the person in the video is, the more their dress and grooming will be pegged to the fashions of the time. If you want to date the video, look at the younger folks in it.
I am thinking that our dress and grooming as we get older is not so much a reflection of contemporary styles as it it an amalgamation of the years of previous fashion we have have integrated (see Arline in the video).