I just finished a huge promotional video project, one which was fraught with problems.
To start out with, most of my interview footage was RED Epic material, and my b-roll was comprised of a combination of RED Epic (some at 4kHD and some at 5k), RED ONE (some at 4k, some at 3k), XDCAM-EX 1080p, HDV 1080i, Sony AVCHD 1080p, previously exported Vimeo HD h.264 material, and still shots. Needless to say, quite a mess of codecs and odd file types to combine into one project.
Since much of my b-roll was 1080p, I decided to do my entire edit on a 1080p timeline; however, since all my interview footage was RED, I decided to use a RED Epic 1080p timeline. In doing so, I discovered something important about Premiere, and I don't know if this is a bug, or if it's meant to work this way: when you put 5k RED Epic material on a 1080p timeline and use the zoom controls in the motion effects panel to bring it to size, and attempt to export, you'll get the "Error Compiling Movie: Unknown Error" every time. This may happen with other types of footage that's too big for the timeline too, i'm not sure. However, when you instead right click on the clip and use the "scale to frame size" command, it exports just fine, with no errors.
I also discovered that (at least with my setup), PrPro can't handle large stills on the timeline; I contiually got OpenGL crash errors until I resized all my images in Photoshop to be no more than 1920px wide.
The promo video is 11:30, and comprised of five segments. I edited each segment (interview and b-roll) in it's own sequence, and then nested the sequences along with the transition/motion graphics/title slides between them on my master sequence. However, I kept getting crashes and freezes when attempting to export that master sequence which I couldn't explain. Ultimately I had to export each of the individual sequences as a Lagarith UT AVI file, and then import that file back in and place it in the master sequence where the nested sequence had been. Once that was done it exported fine, so I'm still not sure what the problems were, since each individaul sequence exported okay, and the master exported just fine after replacing the nested sequences with the Lagarith clips...
Anyway, I think I've got a pretty good promo done, and it's definitely a TON better than our last one. When I get it online I'll post a link over in the Lounge and ask for feedback...