It's quite strange because if the work folder couldn't be created, I think that the video creation process would abort much earlier.
Maybe, try to set the com.eteks.sweethome3d.applicationFolders Java system property equal to a folder where you're sure you can write, for example by writing: in a text file named SweetHome3D.l4j.ini and saved in the same directory as SweetHome3D executable files.