Having used Blinkbox and Film4od in the past, I thought I would give Sainsburys VoD a try - had a 99p rental voucher.
So after a bit of a faff, got the voucher code to be accepted. Registered on the site, credit card details etc. Then installed the Divx player thingy that is needed.
All seemed to be going well. Then Chrome crashed when trying to play the movie. Tried again, same thing happened. Tried several times, having rebooted, same thing happened. Now the Sainsburys site said I had not more licences. So called Sainsburys Customer Services, got through quickly and they said to try IE and that they will add a couple more licences so I could get the movie to play.
IE worked, for about 4 minutes, then Windows7 crashed.
Reboot... Then tried the Download Manager. That worked and now I have a WmV file that plays in Windows Media Player.
Have you tried Sainsburys Video on Demand! Did you get it working or have similar trouble to me? In my case the download option seems to work, so sticking with that.