Move files from multiple subfolders to a big one
FOR /R "C:\SourceFolderPath" %%i IN (*.html) DO MOVE "%%i" "C:\TargetFolderPath"
Save the above in a .txt file; rename the extension to .bat and run it by clicking on it, but first:
C:\SourceFolderPath = path of your subfolders
C:\TargetFolderPath = path of the new big folder
*.html = the type of files you want moved