As a quick fix for those running version from repo, change:

BASE_MSN="https://www.google.com/search?site=&tbm=isch&q="
MSN_MEDIUM="&tbs=isz:m"
MSN_SMALL="&tbs=isz:s"
MSN_SQUARE=""
MSN_PHOTO=""

Further down there are some references to "imgurl:"" change to "imgurl="

Now you should have basic working google image results instead of bing. Still testing at the moment. I'll clean it up, correct functions using some of the extra details from above posts code, minus engine option as I don't have a working bing version at the moment. Ideally I'd like to make a version which uses script files from albumartdownloader (uses "boo" script?) so that they can be kept up to date.