Virtual Samba Schools
These are online samba schools. They parade in two rival leagues, Virtuafolia and LIESV, and the praades of the latter are happening on the weekend of 18th August at www.liesv.com.br. You can only see the whole parade live as it is happening, so if you miss the parade you will have to wait till next year. It starts at 9pm Rio time, which at the moment is 1am UK time, and goes on for around 4 hours. Each school parades for about 30 minutes.
To read more about these virtual samba schools, have a look at http://www.tdsounds.co.uk/rio-carnival/samba-schools/192-the-virtyal-samba-schools-of-brazil.