Quicktime files are compressed and if your movie is large it may need time
to decompress. You can try transcoding from Quicktime to MPEG. This delay could also be caused by file caching size.
The Cut to black during page wipes can be caused by unmatched resolutions between the pages. You can try changing the resolutions in Options from ‘Adopt’ to a fixed resolution. You can try adding Fade transitions on the page you resolve to. Remember Cuts on the first page do not take place until the presentations loops back to the beginning.