I found that I can preview the down load by waiting until one MB is down and then asking my VLC Media Player to play it. I go to the download folder - in my case "Incomplete". Other players won't play while the download is in progress. Sometimes I'll immediately know if I want to keep something and sometimes I'll have to wait until perhaps 5 MB is down before I have enough to get a sense of what's coming down.

Key word filter works - just add the words as they become apparent to you during your searches.