How can OAT and SAT differ?
From the manual:



So it appears that this instrument's terminology is a little non-standard.



Additional information:

From the Youtube video, you can see that they are moving at a fair pace:



If you take these numbers and plug it into the equations from this question,

$$Ram~Rise=SAT\times0.2\times{M}^2$$

(remembering that SAT needs to be in degrees Kelvin)

You come up with

$$Ram~Rise=(273-33)\times0.2\times{0.491}^2 \approx 11.6C_{rise}$$

Which is pretty close to what you see in the video.



Additional, additional information:

Here is the conversion chart of OAT to SAT in the POH for that (or similar) airplane.



No other qualification is given, but my assumption is that OAT is not TAT, and would be wrong to label it that... it is just the raw temperature sensor value.