But I will say for the season 6 premiere, that one aired as a two hour episode and part 1 has a lot of small bits cut from it in the two part version
The streaming version does have a “previously on” segment but it’s shortened compared to the original version
The US DVD at least has that episode in its original format despite editing out that segment
Yup S06E01 seems to have been messed around with quite a bit.
– The broadcast starts with a series recap that lasts about 1:35 beginning with "Previously on Buffy the vampire Slayer: You are the chosen one, you alone can stop them… ".
– The streaming starts with “Previously: I know you never loved me…” and recaps the events of season 5 and lasts about 0:45.
The other difference I noted was S02E10 - which begins differently: “Last week on buffy the vampire slayer” vs “Previously on …” Streaming vs UK broadcast. I don’t have a copy of the US broadcast of that episode, so I’d need to validate against the PAL and NTSC DVDs.
However, in general, the “previously on” segments on streaming seem to line up with the broadcast segments (I spot checked S01E07, S01E12, S02E06, S03E21, S04E22, S05E05, S06E06, S07E01 ) - are you aware of any others that differ ?