I never said you were a fool. You are putting words into my mouth again.I know very well what AMSI is, please don't take me for a fool....
With proper AMSI integration, downloading a file should not be necessary. More sophisticated script attacks download and run a malicious script in memory only; no file ever touches the file system.
Every single time a lab tests AMSI, Norton fails. And it is common knowledge that Norton does not do well against scriptors. Perhaps you should read the many threads about it here at MT in the Norton sub-forum.