This resource has been improved in the 2.0 API with the resources:
We recommend using these new API resources instead of
Buzz Segments can be shared between Accounts on the same Buzz instance in the case of a Multi-Account Buzz installation. To retrieve a list of Segments shared locally,
"source":"local" should be included in the GET request.
More commonly, "third-party" Segments can be shared with a Buzz instance. This is the case with common data providers such as BlueKai, Integral Ad Science, and many others. To retrieve eligible Segments from third parties `"source":"third-party" should be included in the GET request.
Note, the Segment Sharing API method also response to a GET request, but it will return the Segments the current Account has shared with others, rather than those Shared with the Account.