Hi
The buffering is likely the result of Telstra not having enough CVC for that time period to cover all the users they have. Currently the average CVC purchased by RSPs is about 900 Kbps per user. When large amounts of users are on and using the net the amount of bandwidth available for you to stream is drastically cut and then your stream has to buffer to continue providing the show. Netflix and similar need about 2 Mbps of bandwidth to run in continuous mode, and good quality, without buffering. Of course some of the slow down may be due to the people in your block using the internet but this would be an extremely minimal impact compared to the CVC issue.
See the entry in the NBN Wiki:
The most likely fix for your issue is getting the RSP, in your case Telstra, to increase the CVC they purchase, the chances of this happening are very, very, very, slim and is really based on the cost to their bottom line (which is substantial). You could also try altering when you use these streaming services but this may be difficult or unsatisfactory for your lifestyle (including work).
You could also get your connection to the node in your basement checked but this is an unlikely cause of your issue particularly if it runs well at other times.
I also recommend you lodge a complaint with the ACCC about your service. This is because the ACCC are looking into the service provided by NBN Co and the RSPs (the providers to the consumers like Telstra and TPG). If enough people advise of their problems hopefully a better service will ensue after the ACCC has enough proof to take action.
