Indexing Service is no longer supported as of Windows XP and is unavailable for use as of Windows 8. Instead, use Windows Search for client side search and Microsoft Search Server Express for server side search.
The MaxFilesizeFiltered entry is the maximum size of a file that the default filter will process for contents.
If the default filter is used for a file that is bigger than the value of the MaxFilesizeFiltered entry, only the file properties are filtered.
This limit does not apply for the filtering of registered file types.