Google Drive is going to deprecate their free web hosting, which we were using to host our overlays.
So I uploaded our overlays elsewhere, AND because some people were complaining about lag, I activated a CDN service (our overlays will be uploaded in many places over the world, so it's faster for everyone to load).
The change should take 24h to be effective.
Sorry for the inconvenience, I didn't think there was going to be any downtime.
edit (12 october 2016): for those who worry - the problem was solved within 24h at the time ^^