I happened to found this
free flv converter for Windows here:
www.askvg.com/free-download-iskysoft-flv-converter-for-windows-worth-25/
What surprised me was it wasn't supposed to be free. It's a Giveaway from iSkysoft. Before those different formats and parameters or default settings bothered me a lot. After downloaded and used it on my laptop, I found out it's extremely easy to operate and fast to convert. I convert loads of flv video that I downloaded from YouTube (FIFA 2010, Annoying Orange, etc) to iPod touch mp4 so that I can watch them all the time (God I love Annoying Orange! XDD). Besides, I also can use it to convert wmv, mov, avi or mpeg to flv for uploading on my website (I personally run a commercial website). It's fast, convenient and users friendly, and I can't believe it's totally free now!
Check this original link on iSkysoft:
www.iskysoft.com/flv-converter-windows.html