hi I had os 4.2 then upgraded to 4.5 and was able to play videos off youtube and now i cant anymore, when i click on a video it goes to the media player and i get a message saying error playing "can not find web address, verify that is web address is valid" my wife has the same phone and she still can play videos off youtube
Have you tried doing a battery pull? Remove the battery with the device turned on. Leave it out for 15 - 30 seconds and put it back in and allow the device to start back up.
My Curve does the exact same thing. The "fix" was to go into Media settings and turn off "Audio boost" AND "Bass boost". For whatever reason, if EITHER of those are set to "on", I cannot play any Youtube videos either.