Question:
Do you know of any way to find out the connection speed of a site’s visitor and then stream videos at the appropriate bitrate? I’m thinking specifically of RealPlayer.

Answer:
Unfortunately, there is no way to determine the speed of the connection a user has to the Internet. One possibility is to simply ask the user. However, this solution is potentially problematic because due to the nature of the Internet there is no guarantee that the data transmitted from your server to the user’s computer (or vice-versa) won’t encounter congestion along the way. In your case, I would suggest that you create several versions of the content with different bandwidth requirements and let the user manually choose which is most appropriate for them.