I checked this out myself last week following the announcement at the end of the programme that it was available for online viewing. The extract below is from the FAQ on 'watching BBC Two video' ([broken link removed]):
For many programmes, there are broadcast rights restrictions, which do not allow us to show BBC Two programmes and content to people outside the UK. In addition, broadband content is expensive for the BBC to stream, so we have to give priority to people within the UK, who ultimately bear the cost of us doing this through their licence fee.
Some BBC programmes are available via our international services (see
bbc.co.uk/info/channels) or through agreements with commercial broadcasters overseas.