Keep your eye on this site,
http://www.cyclingfans.com/, which lists web coverage for most races. I don't think they have the Tour coverage up yet
I doubt you'll get free web video coverage (
www.cyclingtv.com might have a premium pay coverage). One way to do it is to have the free Eurosport audio feed (
http://www.eurosport.com/cycling/ - under "Live Score"). They also usually have a graphical profile that shows the breaks and peloton time gaps as well...which means you can listen to the live audio and have a visual idea of what's going on and where they are on the stage. I did this for the Giro and it was quite good.
Otherwise you can move to Australia where we get it free to air, every stage live! The only English speaking country to offer this (whoohoo!).