A little late reply maybe, but I wanted to share some experience in the discussed matter.
I have seen that after moving files from SkyDrive Camera Roll folder, I had to wait two weeks until "Storage Check" > "Clear temporary files" actually cleared the files. I assume that might be why some users report that it does not work while others report it as successful.
Now, with over 2 GB temporary files that were not possible to clear with Storage Check app, I was thinking that maybe there could be a way to trick WP8 to believe that there is time to remove the temporary files. So I just changed the date/time to two weeks ahead and retried. It worked and I was back at around 200 MB temporary files instead of > 2 GB.
Now, one could wonder why there is a two-week lifetime for such temporary files. There should at least be a way to adjust that time, or to remove temporary files even if they have remaining lifetime. But anyway, this trick has worked for me a few times now and it is definitely a lot easier than alternatives, such as factory resets or similar.