My 3gp uploaded youtube video won't play -- lack of codec integration

Just smile when I tried to watch a video, I have uploaded someday's before  from my tablet. The video has been recorded using my tablet camera. I upload the video to youtube, also using my tablet.

But, when I want to watch the video using the same tablet, it won't play. The tablet says "unsupported video format".

How come?? Of course the application I use to watch the video, has been failed to recognize that the tablet support that video format. This is lack of codec integration, and it should be better if the app can play the video, without having to install the codec prior it. There should be an Application programming Interface (API) that enable some app that need the codec installed on the system.