As a follow-up to this resurrected thread, yes, I have found freeware called FLVPlayer that does a great job of playing those flv files. It's a standalone application that once loaded autoplays virtually any flv files you save. Here's a link to a newer version:

martijndevisser.com » FLV Player

Any viddy files you view on the internet are saved as temporary internet files (you'll have to find exactly where on your system). As long as you stay logged onto the site, they'll be there. I just copy them to another file.

Regarding stuff you post on the internet: Whether it's pictures or viddys, one has to assume that someone out there just might be saving them. (In fact a person who had collected a bunch of stuff I posted was kind enough to send them to me when I had lost them.)

Have on only one occasion found someone trying to pass my pics off as himself (and it was someone I knew... correction, though I knew). That's a bridge to cross if you come to it.

Better still, if you're that worried about it, don't post em.