Your right their should be no reason to install 3rd party encoders in Deskscape 10
However the fact is on my vanilla Windows 10 system 1903 v 18362.295 , MPeg 2 reliant deskscapes now regularly freeze with or without decoders ,inc Microsoft extension.
All .dream , avi , .wmv etc examples work normally without decoding in Deskscapes 8.51 !
Why is that ?