I don’t recall what year the copyright takedowns began, but about five years ago it became noticeable. In the late 1990s to early to mid 2000s, you could find hobbyists uploading them all over the place. When YouTube got started there was a brief point in time where almost half (or maybe more than half) of all Alan Watts recordings were uploaded. Podcasters like Lorenzo made it even more popular (don’t recall where he got his recording from, but pretty sure he was later served with a takedown notice by the Watts family).