So this is fun: Professional stunt coordinator Jeff Pruitt has a bunch of behind-the-scenes "home videos" on his YouTube channel from his time working on Buffy the Vampire Slayer. It's the kind of stockpile that has a way of devouring your evening whole.
Lots of appearances here by the cast and crew, including Sophia Crawford, Sarah Michelle Gellar's stunt double. Plenty of off-camera moments here, as well. It's fascinating to watch a stage fight take shape. Actors trade blows, slowly at first, and then faster and faster as they become familiar with the sequencing. These videos also highlight the importance of camera angles in making a fight scene look believable. A clear miss can look like a devastating blow when shot from the right perspective.
From the episode "Earshot" (and a bit from "Doppelgangland")
The Opening Fight Scene from "Choices"
Faith and Angel Square Off For the First Time In "Revelations"
Fight Sequence from "The Wish," With A Few Shots of the "hellfight" from "Anne"
The Final Fight Scene From Season 3 Finale "Graduation Day"
The Floating Gentlemen from "Hush," with Additional Scenes from "Doomed"
There's about 20 more of these videos (along with tons of footage from his other projects) on Pruitt's YouTube page. Be apprised: One of the best things about these videos is the commentary Pruitt includes in the description of each one. Look for them.