As far as I can remember, yours is the first ever mention of Revit on the forum, so only some general comments/questions
What codec does Revit create?
900x675 is not a size I have ever seen mentioned... what kind of project, SD or HD?
Did you try the "new item" process? http://forums.adobe.com/thread/872666?tstart=0
Revit allows export animation using MS video 1 or uncompressed full frames. We did
uncompressed full frames. Revit allows you to choose your size,
we just picked something that fit in our view.
Pretty much new to premiere, we just downloaded the trial version Monday.
I don't know if it's SD or HD.
The wierd thing is you can play the video as exported and the background looks fine, load it into premiere and it looks fine in the preview, but not when it's playing. We also exported it from premiere and has the same problem. Backgrounds in Revit are not modeled objects, just an image file that is used during rendering. It doesn't make sense that you can't see this background in premiere but you can when you play the video on it's own.
Hopefully someone has experienced this before.
SD is 720x480 and then you determine regular or widescreen with the PAR (Pixel Aspect Ratio)
When you put the video on the timeline, is there a red line?
If there is a red line above the timeline, you have a mis-match between the video and the sequence... go back and look at the New Item process in my previous message
CS5 User Guides - online and PDF (see link in upper right corner at individual pages)