There are some limitations when using QT movies in a realtime composition:
1. When using alpha channel, the file must be ProRes 4444 otherwise gradients in the transparency layer will get bending. So do not use Animation codec if you have gradients.
2. The pixel size should be kept at a minimum. For example if you want to use a rotating station id (like the one we provide with CBuilder) don't make a full pixel size movie where only a few pixels are used, but instead make the movie as small as possible and position it where you need it in CBuilder.
3. Use the right caching. Preroll only for movies covering app 1/4 of the screen, like lower 3rd backgrounds or animated corner logos. Force into Memory for very small repeating images and Incremental for very long and large images.
Make sure the disk drive holding the qt movies is fast enough to deliver the data rate needed to play out the movie.