This lists the minimum requirements/suggestions for an excellent and a good level of streaming capability.
Essentially the higher connection speed the better. The document suggests a minimum of 1000kbps upload speed for Excellent video quality (350kbps as an absolute minimum for video or you will only be able to stream audio), however considering that you will also be clerking a higher rate would be recommended. It is also recommended to use a wired connection if possible. Finally, where possible it is beneficial to reserve the bandwidth for the stream - this helps to keep the quality of the video up and reduces the risk of quality degradation when other devices are using the connection. It might involve some technical input and/or not be available to you depending on the chosen venue.
There's no substitute for testing it out if possible! Especially if you are using a non-standard configuration such as streaming the video from a mobile device or streaming from a remote location then we highly recommend trying this out before the day of the auction.
Lastly, we always recommend streaming from a different device than the one used for clerking.