iphone 3g safari and youtube video

The problem with my iphone 3g is that the website i use for tech updates where they have a video section and all of them are on youtube format and so couple of weeks ago i when to the website and and clicked on the video and the website said that i need flash player and i was like thats strange because in past i was able to play the videos for the web site so the i went to my home computer and opened the website to play the same video and it is infact the youtube video format. Then i went to the youtube website and i was able to play the videos on the youtube website so i dont really know whats causing this problem.