You did not indicate if this is a corporate phone but it sounds like your service to these sites is restricted. Not uncommon on a corporate device.
If you own it, see if you can go to other sites without problems. If you can then Try this link if your not on a corporate server. KB19091-Error "Content not available. Server is blocked or unresponsive" occurs when attempting to access videos on m.youtube.com from the BlackBerry smartphone