SAN FRANCISCO (dpa) – It's spawned scandals, spoofs and sensations and is probably the biggest time waster on the planet.

But as video-sharing Internet site YouTube celebrated its fifth birthday on Monday, all the signs were that it's just getting started.

The site, which uploaded its first video in May 2005, now boasts 2 billion video views per day, and according to industry experts could soon dominate the future of television.

Google, which bought YouTube in October 2006 for 1.65 billion dollars, hopes those predictions come true. Even though the internet giant is focusing its famous brainpower and cash reserves to make sure it happens sooner rather than later, success may prove elusive.

YouTube users already post more than 24 hours of video content every minute, and the site is the third-most heavily-trafficked on the internet, according to Google. But the average YouTuber spends only 15 minutes a day on the site, compared to the five hours that are spent watching television, and the key challenge for YouTube is to close that time gap.

YouTube is adding rental capabilities for full-length movies, two- hour concerts and live sporting events in a bid to attract more high quality content to its line-up.

''There is only so much time that people can spend watching a cat on a skateboard,'' says new media consultant Derek Anderson. ''If YouTube really wants to displace cable and satellite television, it needs better content.''

One area where it is getting closer is in the quality of its broadcasts. Whereas internet video was once rightly derided for its grainy imagery and stuttering playback, many YouTube videos are now available in 3-D and high definition, and can be viewed comfortably in peoples' living rooms thanks to the growing prevalence of internet-capable television sets and broadband connections.

''Broadcast, internet and user-generated content will continue to converge,'' says Bob Greenberg, chairman and chief executive of R/GA, a renowned digital advertising agency.

For younger viewers the boundaries that separate these different forms of broadcast have already largely disappeared.

''I don't like to be tied to the TV schedules,'' says Kelly Skinner, a 19-year-old student. ''I prefer to watch the shows I want online, when it suits me.''

That shift is already showing up where it matters most to Google - in the company's financial results. According to a press release, YouTube already earns money from more than 1 billion video views every week, with the result that the ad revenue that the company shares with the creators of its content more than tripled in 2009.

That can mean big money for the few videos that go viral, like David After Dentist. This is the snippet of footage that shows a disoriented child still groggy after his dental treatment, asking his father on the car ride home: ''Is this real life?''

That video has been viewed more than 59 million times and still attracts more than 100,000 views a day, earning his family more than 125,000 dollars.