The outage appears to have run for a few hours as of this writing. It's not the first outage in recent months. However, Downdetector data suggests this was severe compared to past incidents, which tended to either be brief or affect a relatively small number of camera owners.
We've asked Arlo if it can shed more light on the downtime. With that in mind, the failure is a reminder that cloud-based cameras are only as reliable as the internet services that power them. Even a relatively short outage could provide a window of opportunity for would-be intruders. The timing is also unfortunate for Arlo -- it just held its public stock offering earlier this week, marking its spin-off as a separate business. While this isn't a major blow by any stretch, it's not exactly an auspicious start.
Update: Arlo told us that it resolved the issue, which lasted between 4PM and 7:30PM Eastern. Your recordings should remain safe.