I've been looking for something like this, well sorta.

Many 'family' cars now come with the option of headrest ipad mounts for rear seat entertainment. This is great, but what about when my kids want to watch the same movie? Showing the same movie at the same exact time on two different ipads would be solve a tremendous pain point for me, and possible lots of other parents!

Well unfortunately it only works on desktop Chrome and Firefox and if we do have something on iPad that would be sweeter :)

Why did you write it? What are the use cases for synchronising videos like this?

A sentence or two in your README to answer these would be handy.

When I'm away from my girlfriend we chat through live audio and sometimes we want to watch movies together. So if the videos syncs we can talk and make comments as if we were together :)

True.

If you're interested, here's an app that uses similar tech for long distance movie watching: https://letsgaze.com/

I'm creating something like this, but as a desktop app in java using VLC api.

There is a screenshot[1] of the current state, but it's a bit ugly since I had to stop working on it because of my exams. The idea is to replace the VLC+Skype combo for watching movies together with automatically syncing the play/pause.

But there is another problem I haven't decided yet, and it's the communication channel for chat and syncing. I'm torn between creating a server on an own VPS or adding an IRC client to the app (since you can always find a free irc server and create a room).

[1]: http://i.pics.rs/jDvun

One of the projects I have on my list which I'll never get around to is distributed group karaoke using webcams. Seems like you should be able to sync both the karaoke video out and the return feed such that you could have a group sing-a-long experience over the web.

Does it also work for the "Live" streams on Youtube? That's the use-case in which I could use the most this kind of synch.

Haven't tried that...it probably won't work. I live in China so YouTube is kinda inconvenient. I connected via VPN to test on YouTube and it should work on most video clips.

Does this necessarily have to be a browser extension or is there any hope of using the video provider APIs to accomplish the same thing?

Of course it will be much easier to use if video sites like YouTube provide this feature. But I don't thinks its that widely needed for them to put it on the feature list.

What I meant to ask is if it's possible with current APIs. I know sync isn't explicitly provided, but wondering if something could be backed together another way.

At first, I thought the app name was "cosplay" :P