Nokia 5130
Cannot play mp4 videos properly

I purchased a nokia 5130 express music, and I cannot play mp4 videos properly, i converted a youtube video to mp4 format it converted and downloaded on the phone fine but when i attempt to play it, it skips video and audio and tends to freeze.

please confirm if this is a known product issue or a faulty unit. either ways i purchased this phone just 2 days back and i want a replacement unit or an upgrade if its a known issue with the model.

regards,

Madhu