The problem is that the HD Buffy seems to have simply chosen at random how to change the program's aspect ratio. Some shots have added visual information at the edges, while others crop out visual information at the top and bottom, making the shot wider, sure, but also removing crucial context here and there. Some shots have even had effects and other important visual cues removed entirely.

Yes, that's a crew member in the shot. The new, wider image now includes things that were cropped out of the original broadcast, including the guy standing just off-camera.

A filter was originally applied to this shot to make it appear that the scene was taking place at night. That filter has apparently been removed, rendering this scene a little nonsensical.

Here you get a good sense of how zooming in on a portion of the shot to make it fill an entire 16:9 screen ruins the composition and removes some of the grandeur of a moment.
Buffy was shot 4x3 cuz TVs were shaped that way. Widescreen Buffy is nonsense. (Firefly was shot wide - Fox cropped it.) #apsectratiowoes
— Joss Whedon (@josswhedon) December 13, 2014