Hi Bikonja, what I wanted to suggest you was to use the BSplayer SDK to create a plugin, but you already found it yourself.
What you can do, to take a screenshot into memory, is to emulate a PRINT keyboard button keypress. This way, the selected frame will be saved into memory and you'll be able to handle it at your wish, for postprocessing or whatever you want.
Beware that the PRINT event could be renderer dependent, I doubt it will work if you choose a renderer which renders to Overlay, but you can do your own tests.
To create a plugin will be useful for you to correctly manage the actual playback time etc.
If you create a plugin, please, share it with us
