Alternatively, if SVN diff is giving you issues and you know which files you modified, you can manually download the original files and compare your modified files with the originals.
On Linux (or Windows if you install MinGW), you could simply run
diff file1.cpp file2.cpp > patch.diff, which will compare the files
file1.cpp and
file2.cpp and redirect the output to a file named
patch.diff. If there are still excess lines in the diff (ie, lines stating changes where none occurred), you could try experimenting with flags like
-E (ignores tab expansion),
-b (ignores space changes), or
--strip-trailing-cr, which strip carriage returns (on the Windows line feed).
If you're doing your development on Windows, which you appear to be from your video, you could use
WinMerge, which I've found quite useful in the past. Not only should it be easy to see your changes in the GUI environment, but you can easily generate a diff (patch) from the tools menu.