This index, and the files that are being indexed, are found online at FamilySearch.org in their collection identified as "New York, Probate Records, 1629-1971, Dutchess, General Index 1721-1862 no 1-15181 A-K." These are digital images of indexes filmed at the Dutchess County, New York court house in 1973 by the Genealogical Society of Utah, and cataloged as FHL film #931616.
The files are found by their file numbers, which seem to follow a chronological order, meaning lower numbers represent files with older dates. The files are in the group of filmed documents titled, "Ancient Documents." Digital images of the files can be accessed at the FamilySearch.org website on the page designated as "New York, Probate Records, 1629-1971, Dutchess." There is no search feature for these images. Finding each individual file must be done manually by working your way through the appropriate film, and locating the first page for specific file can be a bit time consuming and tedious. When I did a search for one file, I found that the first pages for the files, which has the file number, was oriented sideways on the screen. In addition, many pages within the file were oriented upside down. The content of each file appears to vary widely. The amount of genealogical data or material may be small or found to be none at all, depending on the file. If, however, you do recognize a name in this index that may be an ancestor, it certainly is worth making an effort to locate the entire file. A link to the index has been placed in the column on the right side of this page, under Pages. It is a PDF document and you are free to download it for use offline.