What is the resolution of the video you render from After Effects? If you plsy the rendered file in another player, do you see the black border?
I make my composition, export multiple files as .avi's again
I load them up in Windows Live Movie Maker, and use that to load them to youtube.
Why? You can create perfectly YouTube compliant H.264 output from AE and upload it directly. That's probably the problem here - all this going round in detours is messing up your pixel aspect ratio and/or sizes...
I wasn't aware I could make perfect youtube compliant stuff, what setting is it I have to use?
Is it something in the drop down menu when chosing to create a new composition?
Two questions: What are you shooting on that records such a weird resolution? And are you using Export or Make Movie?
I'm recording using Fraps, and isn't the resolution defined by my monitor size because it records everything on screen, if I play back in windows media player straight after recording I don't get the black border.
And I'm exporting by putting it in the render queue, setting the destination etc. then hitting render.
What codec (output module settings). What Comp settings?