I'm going to disagree with the people saying, "oooh, market validation". This validates that Google wants to index more stuff and Flash builders want to get indexed. It doesn't validate that users would go to a vertical flash search engine.
When Google does something in the search game, they are generally going to win. Without the exit strategy of selling to them, you are left with building your own search brand (supported by ads). Are there enough people who are passionate about finding Flash stuff that they'd rather use your (better) flash search engine over an integrated experience at Google?