The primary source of OpenStreetMap data is https://planet.openstreetmap.org. This has the history of planetary-level data sets, but these are extremely large files (50+ GB). Note that YAAC cannot import OSM changeset delta files, only complete data files.
There is a web page of alternate sources on the OpenStreetMap wiki at https://wiki.openstreetmap.org/wiki/Planet.osm#Planet.osm_mirrors, for various subdivisions of the planetary data sets.