Here is what they say (HERE)at RealPlayer's FAQ:

Why is RealPlayer 8 Basic still rebuffering or giving poor playback from many sites? Packet loss occurs when information is unable to successfully travel from one server to another. Previous RealPlayers have interpreted lost information as rebuffering, hissing, crackles, and skips. RealSystem G2 (and RealSystem 8) is designed to minimize the effects of packet loss.

In RealSystem G2 (and RealSystem 8), RealProducer is used to encode RealMedia into streams of varying bandwidths. When RealPlayer 8 connects to a RealServer serving the variable bandwidth content, the server detects your Internet connection speed and sends the best stream possible for that connection. As the quality of your Internet connection changes due to packet loss, RealServer switches to a lower bandwidth stream. This causes a difference in the audio quality, but eliminates the rebuffering, hissing, crackles, and skips. When the quality of your Internet connection improves, RealServer switches back to the higher bandwidth stream. The switching is instantaneous so that there are no breaks in playback.

However, at sites where the content is not encoded using RealSystem G2 (or RealSystem 8), RealPlayer 8 will still rebuffer, hiss, or skip when the connection becomes too thin to consistently support the stream. This is expected behavior.

To minimize poor playback from those sites not using RealSystem G2 (or RealSystem 8), try playing the content during times when Internet traffic is not at its peak. U.S. business hours and weekend evenings are peak times. Connections and playback will be better at other hours.