To revive this topic, FlowPlayer just updated their player so that you can encode a high quality H.264 movie for people with a recent Flash plugin (upgraded since December 2007), but yet falls back to an old-school FLV for people who have not upgraded their plugin.
To me, this is the best of both worlds- a great quality H.264 movie for the hip and savvy, but still a FLV fallback so that Grandma can still view the video on her 5 year old PC (on which she has never upgraded anything).
FlowPlayer offers a free GPL player with a watermark, or various licenses.
Here is the relevant page:
Flowplayer
Our new encoding program,
DV Kitchen, will encode FLV and H.264 movies and upload them, and we will support this smart dual movie scheme with FlowPlayer soon, but for now you have to copy and paste a few URLs from the Media Publishing tab.
I am going to do a tutorial movie on this next week.