Thanks for your post.
Have you tried opening the videos from the YouTube application too?
Is your device updated to the lastest version? If yes, I advise you to reinstall the software. You may update and reinstall device's software from the updates tab in Nokia Suite.
Let us know how you get on and feel free to post any other questions you may have.
I have updated my software, but still my youtube app is not working.. the moment i click on the video to play it says could not connect. My gprs is working absolutely fine as i am able to surf net and various other app like email whatsapp etc. please help me
Youtube has suddenly stopped working for the past 4 months