Video Studio X4
Your video is 1440 x 1080 (4 x 3) as widescreen is anamorphic to produce the 16:9 shape, using Non Square Pixel Rendering to change the 4:3 to 16:9
Flash is not anamorphic so Disable Non Square Pixel Rendering.
Share Create Video File –Custom – Save as type Flash
Disable Perform Non Square……..
User Defined Frame Size to 1280 x 720
Compression tab—data rate 1000.
There is also an option for Non Square in Project Properties (alt+enter)
I am not sure if you have to also disable, I think it depends on the timeline content?
X5 webm gives a higher Data Rate and I assume produces higher quality video, with a larger file size, and longer rendering.
this doesnt work, i get a nasty black border on left and right, no ,matter what i do if i do this is avi i dont have this issue ONLY with flv. There has to be a way for it to fill the whole screen without using the borders. I did everything you said, I can make a video if you like to see what im talking about.