Best quality youtube downloading?

[chane]

Please suggest one or two widgets, "extensions" or "add-ons" for Firefox, Chrome and/or Opera for Windows XP.

I don't need too many features; just something that will download YouTube files in the absolute best video and audio quality
via any or all of these browsers.

Question: At Download.com, I've noticed that many of these youtube downloading programs offer the option to convert
the youtube's original format (usually .flv) to another such as MPEG-4, MPEG-4 AVC and AVI.
All of those formats will play on my new Cambridge 650BD player.

But which youtube downloading program (freeware or payware) might do the best quality job of converting a youtube flv
file to an MPEG-4 or AVI file?

[VLC_help]

This is VLC related?