This will only work if playing the video in Chrome or Chromium-based browsers of around version 80 and newer.
OBS on PC uses v75 though, so it's not supported in OBS yet. OBS will support the buffer command in the future, but currently it does not.
&buffer=0 will force the audio to be in sync with the video, with the video playing back with minimal delay.
Adding a buffer > ~ 100 will add a time delay to the video.
Adding a buffer > ~ 100 can help reduce video problems, such as frame jitter