I'm sure some of you already follow these, but these accounts are great to check out to see swings the pros, usually great angles and slow motion. I'll add more as I discover them.
First up is Sacred Links. I think he's based in CA, he gets some incredible footage, perfect angles, slow motion and puts swings side by side.
Second is David Poulton. This is more photos from books, he must have quite a library. There are some videos. There is more coverage of players in the 60s and 70s.
Twitter - doglegpar3
Third, a recent find, swingsdeclassified. Not as familiar with this, looks like it's also more focused on older coverage.