Web users trying to access the site were presented with pages that featured messages such as 'Http/1.1 Service Unavailable', 'Internal server error. The server encountered an internal error or misconfiguration and was unable to complete your request' and even 'an error occured, please try again later'.
However, the site was back up and running by lunchtime.
Google didn't reveal what caused the outage but it did apologise for the crash.
"We apologise for the inconvenience, but YouTube is temporarily unavailable," Google said at the time.
"Our engineers are currently working to restore the site."
YouTube's outage comes as Google revealed it was to stop censoring results displayed on its Chinese search engine. However it is not thought the two incidents are linked.