AV changed their download policies once again and it ends up breaking the extension. Now you can only download 4 securities before a long wait. So the 5th one fails and it continues to fail for about a minute. AV has limited coverage, and bad values that change from the daily downloads to the closing (change pence to pounds, ignore splits etc.) and keeps changing the free download parameters to get you to pay exorbitant prices.
The hleofxquotes java program works fairly well, but does not download history, high/low/volume numbers. And they will also be working with changing blocks once Yahoo finds them and starts to block them which is their stated policy.