[SeikiS]_Porfy_no_nagai_tabi_03v2patch.zip

Here it is! Instructions are fairly simple:
1. Download the zip file
2. Unzip contents into folder containing [SeikiS]_Porfy_no_nagai_tabi_03_[61DC1621].mkv
3. Execute Run_patch03v2.bat (not the xdelta3.exe file)
4. Give permission to delete files after it's finished

The patch should clean after itself, leaving only your new, patched version behind. It's also supposed to work on both Windows and Linux, even though I haven't had the chance to test it in a Linux environment.