Can only merge files of same resolution

I purchased this software to merge several video clips of differing resolutions together, the description seeming to imply that this was possible, and that you could set an output resolution and have scaling or letterboxing for videos smaller than the full resolution. However, the program refuses to merge video files unless they are already at the same resolution. Before buying this software, please note that it will not merge files if your video resolutions do not match.

macx2000 about Video Merge & Split