Here it is. I could not reproduce the problem entirely. The single first cluster was moved to LCN 2 this time. It will take a while before the situation on the disk will be "right" again, but I send you the logfile anyway. This is what it seems to do:
23:10:35 Starting block analysis for VacateUntilEnoughFree, StartLcn=204176, MinimumClusters=26272
23:10:35 Block: LCN=204176, Clusters=9344, Path='D:\OldFile 1,x'
23:10:35 Block: LCN=213520, Clusters=82954, gap
23:10:35 Block: LCN=296474, Clusters=28706, Path='D:\Big Fragmented File,x'
It notices the gap and sees parts of the file. The gap is 92000 LCN's, where the file to be placed is only 26272 LCN's. So no need to clean any clusters. But MyDefrag does the moving anyway.
The script used might look familiar to you. I am kind of a synergy-minded person.