ESPN3 or mac-sports.com? Either way, could be bandwidth to your house (ISP, congestion in the neighborhood if you're on cable), bandwidth in your house (other users, wifi signal strength if a computer was moved, etc.), or other computer resources (RAM, etc. -- I've often found closing my browser entirely and restarting it during halftime helped quite a lot with ESPN3 streams for football games this fall; Flash can be very prone to memory leaks).
Most streams will continuously evaluate how well your computer is keeping up with the video playback and adjust accordingly (usually streams are delivered in small chunks, which would account for the 10-second improvements - in all likelyhood the program thought, "hey, lets give the higher quality a shot," then said, "nope, not working well enough, back down we go").
Last Edited: 1/31/2013 1:44:22 AM by anorris