Decklink SDK does not provide any Python wrapper, however, it should be possible to use the DeckLink SDK as it is possible to use any other C++ based library in Python.
If you require Python bindings then you may wish to investigate SWIG or Boost.Python.
The developer documentation presents examples in C++, however the content of the documentation is generic as it documents the interface and not a specific implementation.
Please see SDK manual sections "2.4.1 Capture" and "2.4.2 Playback" for a high-level overview of the steps required to perform capture and playback operations.
There is no python sample application which demonstrates using the DeckLink SDK to capture or playback video.