Same here. It looks like a browser problem with playing mp4 files and I'm already fed up with trying to fix it. So I put
Peregrinación 1963 into the YouTube search field. Not only did I get the short video that
@mspath has mentioned but also several movies from the Spanish public broadcaster RTVE about the
Camino de Santiago. One from January 1955 and another one from January 1970. I find them very interesting. It may not be what the OP is looking for as it doesn't have any people walking with a backpack but it shows how present the
Camino de Santiago and its patrimony and heritage was in the collective consciousness in Spain in the 1950s to 1970s, long before most of us had ever heard of it.
http://www.rtve.es/alacarta/videos/documentales-color/camino-santiago/2892519/ (1970)
http://www.rtve.es/alacarta/videos/documentales-b-n/camino-santiago/2845385/ (1955)