If you've been watching a lot of YouTube on your Optus-connected mobile, that may not have been reflected in your data usage measurements. That's likely to change from April 17, when Optus will begin including all YouTube access in its calculations, and billing you accordingly.
In a notice on its web site, Optus says that due to a "technical issue" it has not been counting YouTube viewing as part of the data allowance. That technical issue likely stems from an earlier Optus policy which offered free YouTube viewing on postpaid plans as part of its "social bundle". While browsing on Twitter, Facebook, LinkedIn, Foursquare and MySpace remains free for Optus customers, the YouTube option was removedfor new customers last year, presumably because Optus realised it consumed rather more data than casual status updates on the other sites.
Optus' text message to tell customers of the change didn't perhaps do the best job of explaining the situation:
Any customers accessing YouTube from 17 Apr 2011 onwards will see data charges on Optus bill
As the site makes somewhat clearer, that doesn't mean that YouTube will be charged as a separate service -- simply that it will come out of the associated data allowance for the account. That may not be a problem if you're on a postpaid cap with a decent allowance, but could be an issue if you have a prepaid account, where casual data is charged at 1.5 cents/Kb. The bottom line? Save your mobile YouTube viewing for when you're in Wi-Fi range and life will be less stressful. Thanks Trent for the spot!
Update: Optus has clarified that if you signed up to a 'yes Social' plan that originally included free YouTube, that will remain unmetered for the life of your contract. Those plans were on offer from March 2010 to July 2010, so if you signed up around that time, check your details carefully.