You won't be able to encode H.264 to swf because as mentioned, swf supports Vector Graphics. You can't encode H.264 using flv container either (using ffmpeg, etc) because the authors intentionally prevents this for copyright reasons. You would have to purchase H.264 licenses to encode to flv. (YouTube has H.264 flv because they purchased the license to do so.)
The best thing you can do is encode your file to h.264 mp4 container and create or use an swf player and include XML meta data and tags to stream the mp4 file. Its just like using H.264 flv and the JWPlayer is great for doing this with Flash Player 10.
This worked great for me!!!