A Safari extension that keeps two people's playback lined up. Play, pause and skip from either side, on anything with a video.
Two computers never play at exactly the same rate, so a gap opens up over time. Most tools fix that by jumping the video, which is jarring for whoever gets moved.
Closiq Sync instead eases the person who is ahead off by up to five percent until the gap closes, with pitch correction so nothing sounds odd. You will not notice it happening. Because it only ever slows the person in front, nobody is skipped past anything.
If one of you stops to buffer, the other pauses and waits, then both resume together. A pause you make yourself is never undone automatically.