Sorry for the answer delay, Smode Tech team is in a huge release process.
French lock down does not helps.
I hope you are sound and safe.
I also hope you will follow our Youtube tutorials.
Note that for performances purpose of blending formula, textures are internally computed with alpha pre-multiplyed.
We are not the only software doing that, and to avoid some quantization loss, some file format like the alpha be recorded like that.
But note that it is not the case of all file format supporting the alpha channel.
It depend of the file format, and in certain cases, it also depend of the recording settings.
Worst of it, sometime it depend of the underlying image library that do the alpha conversion internally.
pre-multiplyed alpha is more a computing format than a display/storage format.
I do not know display devices that support alpha channel, sdi keyer often take a simple grayscale channel as alpha, in addition to a second RGB signal.
The typical case for Smode is to convert pre-multiplied alpha RGBA into RGB before draw the content in the video output.
Alpha is matted to black background. But Smode can also output Alpha, via Spout for instance.
Note that ISF Modifier "Show Alpha", only replace alpha channel by 1. (100%).
So this should display the color in an opaque way.
If colors are already multiply, they should appears darker than expected.
Hoping this can helps.